I had a crown fitted several years ago on my lower left molar 2nd to last, I have no wisdom teeth, and now, several years later, I experience moments of pain and discomfort lasting a week to 3 weeks. I am begining to think the tooth under my crown has become infected as even the tooth where the crown meets is beginning to turn black. I also get a bubble of pus on my gums under the crowned tooth that fills and fills until it bursts on its own. These sympoms go away for a long period of time then they return. I can handle the discomfort but it's quite annoying. I wonder if it's time to see the dentist or just let my body try to fight this on its own...any and all advice is greatly appreciated.