Super Sensitive Tooth After Filling?

This can happen from time to time with fillings, especially on molars that take excessive chewing forces.  After a bite adjustment it could take a couple of weeks for the tooth to settle down.  If the discomfort continues I would have the dentist take it out and place a sedative filling.  This will tell you whether the nerve is fine or whether it will need a root canal. 

There was probably some disturbance to the tubules leading to your nerve, thus setting up a highly inflammatory process. Your nerve might survive, or it might succumb and require Root Canal. Take the ibuprofen in the meantime, and perhaps ask him his thoughts on an antibiotic as well, and hope for the best. If pain's not gone in a few more days, consider removing the filling and placing a sedative temporary until it resolves.