Dental Question.. please help!?

[Angelina]

Off and on for about 4-6 months I've had a bad pain in my lower left jaw. My DDS determined I needed a RC and she did the RC in Dec. I was on antibiotics at the time as well. I went back 3 times since then to see why this pain was coming back. She said she could not see infection in xrays, nor by feeling around my gums... and said my body must be having a hard time fighting it off. I was given more antibiotics. I've been off antibiotics for a mth and been ok. 2 days ago my throat was hurting, went to reg MD and she said my left lymph gland and tonsil is a tiny bit swollen but nothing to worry about yet. She agrees a am fighting an infection but she thinks it's viral. I'm going to another DDS tomorrow for xrays again. This will be my 4th DDS and 5th set of xrays to see if there is still infection in that tooth. My DDS was assuming there was because the tooth is still tender. All my RC's are tender though. If I had an infection from that RC tooth, wouldn't I have pain in that tooth? Thku