Also, had jaw pain and trouble swallowing. Was referred to speech therapy, had a Barium Swallow done to watch stuff go down the throat, was diagnosed with dysphagia. I could only open my mouth to barely get a small weiner in. Now after 1 1/2 years after radiation/chemo therapy I can stick 3 fingers in mouth, so it has done very good, but have to do them when I remember. Check oralfoundation.com and it has helpful excersizes on this topic. Still have a little pain occasionally, but not like before. This too will pass as time goes on and it to will get better.
A good excersize given to me is to open the mouth as wide as you can, using thumb and pointing fingers on teeth pushing the teeth open as tolerated, 7 seconds, 7 times a day to start out with. This worked great for me and might help.
Good Luck