first off, at that age, brumation is probably not the reason. They do slow down during the winter but baby beardies usually don't brumate.
Second, the reptiglo uvb tube is part of your problem. That uvb has caused problems. Turn it off and go to petmountain.com and get a reptiSUN 10 tube. Don't get any coil or compact uvb bulbs as they aren't really good. Some have improved but aren't long enough to give the beardies uvb over their entire bodies.
Third, you said your basking spot temps is 90? What are you taking the temps with? The basking spot should be at 95 to 110, closer to 110 for babies. If you are taking the temps with a stick on, the basking spot could be way to hot. I use the accurite digital thermometer with probe and that does good as it measures the cool side where the thermometer is and the probe, you put on the basking spot and the second temp measures where the probe is. The one I have also gives you a humidity reading, unless your humidity is under 20, it only says "lo" at that point. You could also use a temp gun.
