I just got my first beardie on Friday and he gave me a similar scare. Friday night after setting up his home, he ate 1 cricket, so I thought, great, at least he is eating and we are off to the races. Saturday and all day Sunday he ate nothing. He just laid on his branch, basking with his eyes closed. I did get him to drink water both days, and he apparently enjoys trying to sleep in his water. Obviously, I don't let him, so I dump out his water, and leave the moist bowl, and he seems content to sleep in there. He also does enjoy sleeping on his rock, however that one is a bit more terrifying, since he splays himself out, and looks dead.... Not exactly what I want to wake up to...
Yesterday, he ate about 15 crickets, and today, so far, has eaten another 14. My husband is home with the pets all day, so we feed him crickets 5 or more times per day. He will eat 4 or 5, and then stop, we will leave one or 2 roaming around, and come back in a few hours. If they are gone, we drop in one more, and see if we have any takers. If we do, great, keep feeding until he's done. Feed, leave and repeat...
We have been giving him greens, veggies and fruit, however so far, he has not eaten any of it. I also purchased every baby bearded dragon food commercially made, so he has a variety of food to choose from, and so far, only will eat crickets.
My only advice is just make sure he/she stays
hydrated, and give him/her time to adjust.