I have a tooth that had an infection & needs root canal. dentist drained it on sunday & put antibiotics in it. i just finished amoxicillin today. why does my tooth still have a sour taste? i have barely any pain anymore, just cant eat on that side?

Sour usually means acidic, and infections are acidic. It still may be draining slightly. The medications placed in the pulp chamber to help kill off any bacteria sometimes leak outside of the temporary filling.. it may be that, too.

It's probably still infected. Report your symptoms to your Dentist. If infection still active, referral to a root canal specialist may be in order.