Why do I have a toothache four years after a root canal treatment?

Hello doctor,

I am having minor to in some cases moderate toothaches from time to time due to a chipped root canal. I have not had any issues until recently. It has been around four years since I had the root canal done but never went back to get the crown. I have not gone because of dental anxiety. I have not had great experiences at the dentist in my life. The pain and sounds of the tools make me weary. I take pain relievers (one a day usually, maybe two). The toothaches are not so bad, but they are bothersome, to say the least. I take primarily Acetaminophen capsules 500 mg. Toothache details: It is weird. Let me explain. I have recurring moderate toothaches (three to five a day) for a few days in a row, then I have a minor one maybe once a day for a few days then the cycle repeats. It is like a pattern. No toothache has been that serious but I do recall having a couple of low-end severe toothaches that did bother my sleep. Those, however are rare. These toothaches have been going on since two months. They are again, not constant. I do have times when I do not really have much or any pain, the most active toothache time is evening.