I once had a crown fall off on a SATURDAY. My current dentist (who didn't put the crown on originally), opened up his office that very afternoon, just for me, to fix it. He brought his daughter with him (for propiety, I'm sure), but just the fact that he opened the office for me! And didn't charge a fortune, either.
Yes, you should leave your original dentist and change. I'll add my POD to the others. There *are* dental emergencies, frequently.