I am having extreme soreness in my mouth, far back in the hinge of my left jaw. I have had no injury of any kind to cause this. I have rheumatoid arthritis which affects my hands, legs, feet, and am on medications (Methatrexate, B-12, injections weekly). Could arthritis be causing this distress in my jaw or does this sound like another problem? Problem has persisted for about 5 days and is a bit less painful each day.