A month ago, my teeth felt completely fine. Then, because my dentist recommended it, I let him pull out an old filling and give me a temporary crown. (He said,"Better tow years too soon than two minute too late.") The molar stopped aching from all the work after a week, but the top and bottom premolars on that side started to ached and became very sensitive and nervy. I figured he altered my bite. I stopped chewing on that side and it got a little better.

Today, he put in the crown, I told him about the premolars and he said not to worry, would probably subside. I came home chewed some soft rice on that side (not thinking) and then realized I must have been still a little numb, because when it wore off the pain was pretty bad. I can't eat anything cold or hot, can't chew. All the teeth on that side of my mouth are tender, like I'm having orthodontia, even my incisors. And the two premolars are easily 8s on a scale of 0-10, throbbing constantly. I ate mashed potatoes for dinner. The other side is fine.

I like this dentist and he says he'll see me tomorrow.

But any advice? Is this fixable? I'm afraid I'll need a root canal on one of these premolars. It has a history of acting up, though it's been fine for 5 or 10 years.

asking,

The dentist should take an x-ray of these teeth to be sure there is no pathology at the tip of the roots. If there is, then yes a root canal will be in order.
He may just have to spend a little more time adjusting the bite and perhaps take one of the teeth out of occlusion so you aren't irritating it when you chew but he really has to figure out which one is the culprit.

I hope you get this resolved soon.