Bitter taste in mouth after tooth extraction/bone graft. Still have it 4 weeks later. Dr says tooth looks great and taste is not from that. Thoughts?

Bitter taste. Bitter taste in the mouth can be from all sorts of causes. Merely listing them won't really help you. Did you ask your own dentist what he/she thinks are the possibilities even if it's not from the extraction? Did you ask if you should consult with your own physician? You need to be evaluate by both a physician and a dentist to figure this out for you.