When I was at the Reptile show last Sunday I went to a talk by a reptile vet from the Phoenix area. He said that a great majority of the reptiles that are taken into his office with illnesses, those illnesses are due to husbandry issues.
This said, I would like to know what size of tank you have the baby in. I also would like to know what you take your temps with. I have my newest baby in a 20 gallon tank. I found out before I got her that a 75 watt house bulb makes the basking spot way, way to hot. The 60 watt house bulb I used made it to cold. I had to use a 60 watt bulb and raise the basking spot up to make it the correct temp. Last Monday I set up the 40 breeder tank for Speedy and moved Zoom Zoom (speedys new [?] sister) into the 20 gallon. I only use a 75 watt for the 40 breeder tank, of course the basking spot there is up toward the top of the tank.
When we got Speedy 5 weeks ago the mother told me that they had trouble getting the temps at the correct spot in the winter. I believe speedy was to hot in that tank because when I got her home with the tank they had for her, I noticed she had one of those 6' ruler sized stick on thermometers, but she put it on the OUTSIDE of the tank. She had NO IDEA of the correct temps inside of the tank as the best way to get the good temps is by using either a digital thermometer with probe or with a temp gun. I'm beginning to think I need a temp gun to correctly get the correct temps where my girls are at because they tend to sit on the probe, which doesn' help.
What could be wrong is that your beardie is too hot. The only way a 100 watt bulb would be good enough is if you had a very large tank. It is suggested to give beardies a soak in warm, not hot, water for 10 to 15 minutes 3 times a week, unless they are really dehydrated, in which case the times per week need to be increased.
I hope this novel helps you a little to figure out what's wrong. The reptisun 10 you are using is good, how close can your beardie get to it?