[Moved here from General Discussion forum due to the serious nature of this beardie]
I agree with the others, he needs to be seen by a reptile vet ASAP. He is extremely thin and also dehydrated as you can tell by looking at his sunken eyes. Since he isn't eating and still pooping 1 to 3 times a day, he could very well have parasites, possibly something more serious as he also shouldn't be losing wt so rapidly. Do you have any pictures of him from when you first got him?
As Taterbug mentioned, it would be a good idea to pick up some vegetable baby food like squash, sweet potato or green beans, you could even put a very small amount of chicken or turkey baby food with it, hopefully he will lick a little of that off of his nose. If you haven't been
bathing him, you should start doing that right away in a transparent plastic container with a washcloth or small towel down on the bottom. Add just enough water to cover his legs and let him soak. If he isn't strong enough to hold his head up, you will have to support it in your hand so that his head doesn't go under water.
As SkeptiBee said, we will need a run down of your setup. To save time, I'm going to post a list of questions, please answer as many as you can so we can try to help him until you can get him to the vet.
How old is your dragon?
What size enclosure do you have your dragon in?
What type substrate do you have on the bottom of your tank?
Do you use UVB lights?
If so, Is it a coil, compact, fluorescent tube, or Mercury Vapor bulb?
What is the brand name and number of your bulb? Wattage (if MVB)?
How old is your
UVB bulb?
How close can your dragon get to the UVB?
Do you use a separate basking bulb? What kind and what is the wattage? Is it a white or colored bulb?
What are the basking temps?
What is the cool side temp?
Do you take the temps with a stick on thermometer, a digital thermometer with a wire and a probe end or a temp gun?
Where exactly are you taking your basking temps?
Do you use a heat rock or heat pad?
What do you feed your dragon? Please be specific.
How often do you feed and what time do you feed (morning, afternoon, night)?
Do you gutload (feed) your crickets, worms, etc?
Do you use vitamin or calcium supplements? What brand(s)? How many days a week do you use each of them?
Do you
bath your dragon? How often?
Do you mist your dragon or offer water other than in the
bath?
Have you gotten a vet check and fecal done?
I also would not recommend getting another beardie especially now since this one is so sick. If you decide to get another later on, it would need its own tank as they are solitary creatures.