Had root canal done through crown 8mths ago after experiencing cold sensitivity extreme. Started hurting beneath it and up into lower jaw, up to ear. Didn't hurt to chew on it, but now it does, (after 6wks). Dentist took out of occlusion, been back to endodontist, he says root canal looks good on xray. Have been on Penicillin 500 for 5 days, pain subsided, but came back. I am a clencher and grinder, and wear a nightguard. Went to TMJ specialist, and he thinks since it hurts on upper, then lower and into jaw, that possibly the ligaments of the root-canaled tooth are inflamed, from grinding/clenching on it. He took nightguard out of occlusion(small amt). He put me on motrin 800/3 times day, and a muscle relaxant to sleep with. Told me not to chew on that side either. I have had some relief about 5%, but tried a small amt of chewing on it and caused flair/soreness of pain. I go back to TMJ specialist in two wks. Endo said he would redo root canal, but he didnt' think it necessary. Any idea of why this is happening? If it is ligaments?, how much pain does one experience with this and how LONG?