My back molar was extracted 4 days ago. very difficult extraction and i had a bone graft as well. i'm still in very much pain. is it normal?

Extraction pain: Everyone heals at a different rate. And pain sucks. When a tooth is sectioned, bone removed) takes longer to "settle" down. Did you follow all the rules for post surgery? Occasionally pain after 72 hours indicates a "dry" socket--the bone is exposed. You may need a narcotic pain reliever. It would be best to contact the dentist and schedule a follow-up for monday.

Some pain is normal: You had a complex procedure. There is going to be some discomfort. If this is increasing then you need to return to surgeon immediately.