Sounds like he might be cold, he needs a basking spot of around 105+ during the day(very important) on one side of tank and cooler on the other side. Night time temps should stay in the 70's for babies and they should be eating all the time.

Beardies sleep for weeks in the winter when they brumate but babies should not be brumating but may if they are cold.

I put small worms in my bowl of greens and the movement and accidental bites of greens as they eat the worms helps them develop a taste for them.

Check temps and make sure you are giving calcium and vitamin supplements with insects as babies need it to develop proper bone structure.