I chipped a bone in my kneecap once when I was a teenager ice skating. I could move the bone around my kneecap with my finger! I had it for quite some time until it finally dissolved on its own.
Did you ever hit your jaw on something, that you can recall? Do you have any pain with your jawbone? Cancer is typically very painful. Typically people don't eat when they have Cancer. Do you have a healthy appetite? I have a brother who died of Leukemia, another brother who has Thyroid Cancer, my husband has brain cancer (Glioblastoma Multiforme) and my Dad has Prostate Cancer. I feel like I have a lot of cancer knowledge since my life has been consumed with it for 27 years. I personally have never heard of jawbone cancer, but there is such a thing as bone cancer. I'm not a Doctor, but tumors are usually attached to something in your body and I don't think you can move them around with your finger. Maybe the next time you visit the Dentist for a cleaning or check up, you could bring it to their attention. Make sure you tell them that it bothers you if they try to make light of it.
Good luck, I'm sure you'll be fine.