Allana, I had exactly the same problem. One of mine was basically sleeping most of the time, eyes shut when crickets are running around it, and didn't eat for a few days. It was very thin and I was also very concerned.
I don't know about yours, but mine was shedding and they can go off their food. After about 4 days it eventually ate again, and is eating regularly.
The beardies are like that - they won't all eat every feeding, often will just watch the crickets walk past. I know its stressful but give it a few more days and see. The other thing I did was (just between you and me and a million internet users) was wound some crickets so they could wriggle but not get away, put them near it and see if eventually it might take one. Even if it just gets one to keep its strength up.
But it does happen - I still get a little worried when the little ones don't eat (2 of them are greedy fat buggers so they are no problem), the other 2 aren't as nuts about food.
Good luck.