What Causes Pain In Jaw Towards Back Of Mouth With Difficulty Swallowing?

Last night I began to feel discomfort in my upper left jaw towards the back of my mouth. Today I awoke to find I couldnt open my mouth more than a 1/4 of the way at all, and even that caused pain. It has started to become slightly uncomfortable to swallow to. I have had a flue for the last few days as weell, is this the problem or ist it unrelated, if so what is it?