Bearded dragon mouth sore

Question
We bought a young bearded dragon about 3 weeks ago. He eats well and is energetic. He has what, at first, appeared to be sand crusted around his mouth. It comes off with warm water and gentle rubbing with a paper towel, but seems to be getting larger. What I thought was sand initially may actually be some sort of sore.
At this point, when it reappears, a small section at the side of his mouth will not open.
There is no visible drainage or bleeding, even when his mouth is open and there are no other spots apparent elsewhere on his body.
He has a habit of rubbing his mouth against the rock in the tank - presumably to get this off.
Any suggestions?

Answer
Hello Amber,

Can you post a picture of that area?  It sounds like he had a mouth injury of some sort & the area keeps trying to crust over or heal & continues to drain.
You will need to get some betadine from the grocery store & dilute it a little bit & then put some antibiotic ointment on it to help get the infection taken care of.
My first thought is mouth rot.
What type of tank setup do you have? What are the temps in the tank, & what type of thermometer are you using to measure the temps?  A stick on thermometer, a digital probe or a temp gun?
What type & brand of UVB are you using?  A flourescent tube bulb or a compact or coil light?  What type of basking light do you use?
I would remove the rocks so he doesn't continue to rub his snout on that.

Tracie