Hi, I'll try to be as direct as possible with you in a constructive way here, as I think your issues are very easily fixed, but you must fix them ASAP, because at your Dragon's age he needs to be getting 13-14 hours every single day of strong, adequate
UVB light and eating a ton of live, healthy, appropriate staple insects, as Dragons do most of their growth and development during their first year of life, and when they suffer from a Calcium Deficiency and the start of MBD during their first year of life, or they don't eat enough live insect protein during their first year of life, they typically end up stunted in size and with permanent physical disabilities.
I would first advise you to dump out all of the Calcium sand immediately, please do not wait until this weekend, you don't need to worry about whatever permanent, solid substrate that you plan on using, you just need to get that sand out of his tank immediately. His GI Tract and bowel movement issues are almost certainly due directly to the Calcium Sand. Dragons lick everything, it's a type of "sixth sense" to them, for touch and exploration, and unfortunately Calcium Carbonate sand turns into hard, cement-like rocks inside their stomachs/GI Tracts. This is exactly the reason he vomited, and when Dragons vomit due to a bowel impaction/obstruction it is a very, very serious issue that can end-up being life threatening. The other issue with any type of loose substrate and Dragons is that they all harbor/breed tons of harmful microbes, including bacteria, fungi, parasites, etc., and since Dragons are very prone to Upper Respiratory Infections, GI Infections, Skin/Scale Infections, and Eye issues, when you put any loose substrate in the bottom of their tank, they are at a very high risk constantly for these infections. But right now the main issue with your Dragon is that his GI Tract is full of very hard, cement-like little blockages that are backing up inside his intestines and into his stomach, which is very dangerous.
Please dump the Calcium Sand out ASAP, disinfect the inside of the tank, and then just put down disposable paper towels that you can throw out and replace as they become soiled. You can worry about getting him a permanent, solid substrate, like textured tile, non-adhesive shelf liner, carpeting, etc. whenever is convenient for you, but for right now he cannot take ingesting anymore of that Calcium Sand at all.
The other major issue that you need to remedy ASAP is getting rid of the Coil
UVB bulb. Not only are they in-general far too weak in their UVB output for a Bearded Dragon (most Coil UVB bulbs are only 13 watts at the most), but ALL Coil/Spiral UVB bulbs seem to cause horrible neurological damage, eye damage, blindness, seizures, etc. Plus, if you have the already too-weak Coil
UVB bulb on top of a mesh lid to the tank, the mesh is blocking about 40% of the already too-weak
UVB light emitted, so essentially your Dragon is getting very little to no adequate
UVB light. Dragons are desert reptiles that are "built" to bask under bright, natural sunlight all day long, every single day. Without him getting 13-14 hours every single day of strong, adequate
UVB light and bright-white colored Basking Light (these 2 lights over the Hot Side of his tank and directly over his basking spot/platform replicate natural sunlight), he is not absorbing any of the Calcium that he is ingesting in his food or from the Calcium powder you feed him, nor any other necessary nutrition in-general that he's eating, he's simply excreting it. This causes his body to leech all of the Calcium from his bones. This is a very, very common issue for pretty much ALL owners who use Coil and/or Compact UVB bulbs for a Bearded Dragon, and is the #1 cause by-far of young Dragons who lose their appetites and become lethargic.
So while the Calcium Sand is no doubt causing a serious bowel obstruction, their is most likely another cause to why he has no appetite and is lethargic, not moving, not basking, etc., and that's a lack of
UVB light. We see this quite literally every single day, multiple times a day on this forum, and is typically turned-around and there is visible improvement seen within 24 hours of the owner turning off the Coil
UVB light, and then putting them under a long (18" or longer) UVB tube inside a long tube fixture that has a metal reflector inside it, that sits behind the UVB tube. This ensures that the Dragon gets strong, direct
UVB light directly underneath the long UVB tube while sitting on his basking spot/platform that is directly underneath the UVB tube and the bright white colored Basking Bulb, but also throughout his entire tank.
To emphasize the difference, a T5 strength UVB that has a minimum UVB output of 10% (or a 10.0 UVB tube, no lower) has a wattage of 24 watts or higher, while most Coil and Compact UVB bulbs are a max of 13 watts, and they have no reflector behind them. I don' know which Coil
UVB bulb you have, but in-general, you have to have Coil UVB bulbs totally unobstructed by anything, like a mesh tank lid, and then within at leas 3-4" of your Dragon's basking spot/platform at all times for them to get any adequate
UVB light, which you cannot safely do with a Coil
UVB bulb, putting them that close to your Dragon will cause eye damage, no doubt.
In contrast, you can spend about $60 shipped on Amazon.com for both a T5 UVB tube and fixture with a refletor (the cheapest place to order both a T5 strength 10.0 or higher UVB tube and a T5-rated fixture with a reflector included)...Either of the brands Arcadia or Reptisun 10.0 are the absolute best in UVB output, quality, strength, and safeness for your Dragon, and are the 2 brands that pretty much all experienced Dragon owners and breeders solely use...You can order a 22" Reptisun 10.0 T5HO UVB tube for about $25 shipped, and then also they have one particular 24", T5-rated tube fixture for it that includes a reflector with it (crucial) for about $28 shipped.
You can have a T5 strength UVB tube sitting on top of the mesh lid, they are strong enough (a much weaker T8 strength UVB tube must be strapped to the underside of the mesh lid). The T5 UVB tubes must only be within abou 10" of your Dragon's basking spot/platform (weaker T8 tubes must be within at leas 6"). And T5 tubes only need to be replaced once every 12 months, while the weaker T8 tubes and all Coil/Compact UVB lights absolutely must be replaced once every 3 months or every 6 months, depending on which they are (T8 tubes and all coil/compact UVB lights have very fast
UVB light decay-rates, so at 3 to 6 months old they no longer emit any
UVB light, they will turn on and light up, but only emit UVA light)....
