Cracked Crown replaced and now have pain in tooth next to crown.
 

I was wondering if anyone could help me out with an issue I'm having with my teeth. It regards the last two teeth on the upper left side of my mouth. The crown cracked on the last tooth and I had it replaced recently. While I had the temporary on I was feeling extreme sensitivity with hot, cold and sharp pain when biting down on something like a cracker. I had no previous pain. I thought it was just sensitive because I had a temporary on, but after I had the permanent crown put on I had the same pain and sensitivity, but not as extreme.
When the permanent crown was put on it was done quickly and there was no adjustment(drilling) of the new crown. I had told the dentist about the sensitivity and he said the tooth is probably sensitive from having work done on it and give it a week to calm down, if I still had an issue, call him in a week. After a little more than two weeks I still had the same issue so I went back to the dentist and pinpointed exactly where the pain was(back right corner of the tooth), it turned out to be the tooth next to the last(newly crowned)tooth. The dentist said because of the fit of the new crown my bite was putting pressure on the second tooth.
Now, this second tooth is a double root canal tooth and I was not having any pain prior to this procedure. The dentist then used the drill to reshape the root canal tooth and it seemed to feel a little better. He also took an X-ray and said the root canal tooth might be infected but he had to compare the X-ray to one taken over a year ago to be sure. Anyway, after I left I could now bite down on food(like crackers) and not feel the sharp pain, so the tooth felt better. But it still had some sensitivity and a little aching. I grind my teeth at night(I wear mouth guard) and sometimes during the day under stress I clench my teeth together and it is during these times, when I wake in the morning, and throughout the day under stress where I'm feeling pain in the tooth.
So, I'm wondering if I'm feeling this pain because my bite is still not correct? From what I understand root canals are often infected but not sure this pain is because of infection since I didn't have pain before this new crown.