TromboneChat

I have 2 problems I am trying to fix. But will only state one here. After playing for serveral hours, I get sores (not open ones) on the inside of my lower lip. I have tried playing PP, shifting my embrochure, staying in the low and middle range, but I still get them. Sometimes it hurts like hell. Any suggestions or advice?

Teeth? Your lip might be riding the edge of your teeth.

I'd have to see you play to give any valid advice.
There are several possible issues and they're probably closely related to whatever the other problem is.