3 months ago I had a filling replaced on tooth #30, (it had separated). 2 weeks later my tooth starting hurting again...Dentist said that it was a large filling and will eventually need a crown. Crown prep was done 4 days ago on tooth #30. Since then, the tooth has been aching around the clock. This pain is not due to my bite. Went to Dentist yesterday and he said, looks fine just take Motrin. The 2nd part of the crown is scheduled for 2 weeks from now. This is keeping me up at night. I need to know:
1. What could cause this constant pain?
2. how long should this continue?
3. Could I need a root canal?