A baby beardie up to 8 months of age needs at least 2 feeding sessions every single day, 10-15 minutes long, where he is allowed to eat as many live insects as he wants! So yes, he should be eat way more than 13 crickets a day, he's not going to properly grow! Usually if using small crickets or dubias they are going to eat at least between 40-60 a day, so you really need to start feeding your baby a lot more. My guys get 3 unlimited feeding sessions every day with live insects (NO FREEZE-DRIED OR DEAD!) between hatching and 8 months, then I cut them back to 2 a day. They eat pretty much the same amount, it's just spaced out more, but using BSFL or dubia roaches they eat between 40-60 a day.
You can order online from
www.dubiaroaches.com (they have all insects) or just google search "live crickets for sale" and compare prices. You can set up repeat shipping to occur every so many weeks. Babies typically eat little to no greens or veggies until about a year old, and you cannot feed them freeze-dried or dead insects because they cause impactions and have little to no nutritional value, and they won't typically eat pellets, so you absolutely must start buying bulk live insects! 13 a day is going to stunt him and cause deficiency diseases like MBD and Vitamin B1 deficiency. Typically for one baby beardie up to a year or so old, you're going to pay between $35-$50 a month for live insects if you order online. Pet shops are usually really expensive unless you are lucky enough to have a privately owned one that is better priced. But seriously, please start feeding him much more, he's going to have problems if you don't, plus he's starving, that's why he always wants to keep eating, you have to feed him until he's full twice a day!
To the OP, it sounds like parasites and a bacterial infection, you need to take a fresh poop sample to your vet and he'll need medications to get rid of them, without a vet he's going to get worse and worse, and start to lose weight because the parasites feed on his nutrition inside of him. So please make a vet appointment and get him on the necessary meds ASAP.