Sensitivity after crown and root canal

I had a crown replaced 6 mos ago.  I have a many crowns and have never had an issue with the procedure or aftermath.   The dentist seemed to think the crown needed to be replaced as I had slight gum bleeding when I flossed.  Otherwise I had no problem with the crown which was almost 6 years old.  It is on #12 upper.
The new crown never "felt" quite right and I returned to my dentist 3 consecutive times during which he proceeded to "remove" decay.  This surprised me as I never had decay removed after a crown was placed.  After the 3rd visit, he sent me to a periodontist as he told me he could do nothing else to help me and maybe I had a gum issue.  The gum around the crown had (and still does) a small inflammation on one side of the crown which throbs.
The periodontist performed a small surgical procedure and told me he saw no issue with either the gum or crown.  He then sent me to an endodontist.  I was told I needed (and got) a root canal done.  It appears the root canal went well and there are no issues the endontist can see on that plane or with any canals.  As I still have the sensitivity and mild throbbing in the tooth, he suggested I go back to my dentist to adjust the bite which I did.  BUT I still have the same mild discomfort I started with 6 months ago after the initial crown replacement.   Any advice would be warmly welcome.