Had a crown on my tooth which didn't hurt, the dentist said there was a hole behind so I replaced it, now there's pain. Advice?

Since having this done I had pain first with the temporary crown so decided root canal to help. I have now had this done and the crown is now on, but I constantly get shooting pain, throbbing, can't touch that tooth as painful and hard to eat on the right side. been back to the dentist several times had exrays done and can't find / see any thing wrong , they now say my only option is to extract the tooth but I never had any pain with my original crown. What can I do I don't want it taken out.