For The Last Three Months I Have Had A Sore

For the last three months I have had a sore jaw (left side) and slightly puffy face on same side. My husband can't notice the puffyness but I can. My jaw hurts but I can't really explain how. The feeling is something I haven't experienced before, it hurst but not all the time. I went to my doctor and she gave me a cream for the inside of my mouth but it didn't improve. I went to the dentist to see if I had an abscess with a tooth. No issues with the xray. They told me I was grinding my teeth while I slept and gave me a plastic device to wear when I slept and it would go away immediately. It has been a week and really no improvement. Any ideas what is wrong?