I had a pretty big cavity on my right back molar. The dentist recommended I see an endodontist. After tests, no root canal needed. I had crown prep the next day. After 3 days it started aching. No worse eating, just a constant pain. It goes away with ibuprofen but returns after 8 or so hours. I had the permanent crown placed 8 days ago and still feel the same pain. I was seen this morning and the x ray/ice test/tapping showed no sign of infection. Is this normal? How long should it last?