Canckor sore in mouth after bitting area . i think stress makes it worse. well it hurts more when i'm tired and stressed?

Come and go: Canker sores come and go. They are commonly felt to be stress related, but I am not sure that is always the case. I do not believe they hurt any less when things are less stressed either. Orabase - a steroid in a sticky paste works about as well as anything.

You are correct: They can be very painful. See your doctor.

Anti inflammatory: Oral aphthous ulcers are as you described, often start with minor trauma such as a bite, and worse with stress. It is not an infection but an inflammatory condition. Without treatment, it typically heals within 7-10 days. To speed up the process, your doctor will likely prescribe you a topical steroid to apply to the area. The sooner you start treatment, the shorter the course of flare.