If for 3 years there is no pain only here & there like every 7 months & thats only for a few mins then is this infection serious? does it mean it hasnt spread to jaw or anywhere, can the dentist know where the infection has spread by an x-ray?
If the tooth was infected you would have severe pain and it would need an antibiotic straight away. If you are only getting pain now and then it may just be sensitive. If there is slight decay it needs to be sorted to prevent infection. I would ask your dentists opinion, they can do an x-ray if necessary and see what is going on.
Just go to the dentist!
oh i would defo sort it out toothach is a nitemare and you mite have to wait weeks for a oppointment