Why does my tooth still hurts after 3 months of a root canal and crown?

I recommend you find another Dentist to rule out possible fracture or micro crack in the root, and also to check if there are any other lateral canals (auxiliary nerves that was missed) and needs to be filled !I do recommend you do see another Endodontist.If all checked out fine, then the fit of your crown might be compromised and it is impinging too much in your gum. The sooner you check above the better off you are. Definitely rule out and make sure your tooth is not cracked, and the fit of your crown is satisfactory.

Thats not normal, root canals should be something that makes the teeth do not hurt,but technically speaking when we perform a root canal, we just remove the 80% of the pulp of the tooth, so there is always a chance of either a secondary pulp conduct, or an accessory conduct.provably what you need its to have another look at the root canal.and also another thing,could be a high spot that its touching first from the other teeth,this may cause that this tooth will hurt, a clinical examination would be your best choice and also percussion vertical and lateral.