A little help please

[n8whitie]

So heres my situation. I just came home today and pulled my red-tail out from hiding under the substrate and his whole head is all swollen.It looks like he just had some major dental work.
he is also acting kinda weird too.I just went back to look at him right now and it has kind of gone down already but his lower mouth is still puffy.
Any takers on this one?
I fed him a small live rat two days ago but he wasnt bit or scratched by it, I watched the whole thing.Im switching to pre-killed anyways.
Please help me on this, I am puzzled as hell.

Thanks , Nate