Need help with extracted tooth?

Ok here it goes, I had a bad tooth for 2 years, yes long time...it became abscessed and was treated but I did not get it extracted, in hopes of saving it. Well I never could save it...I don't know if it became abscessed again or infection never went away...But it started to get painful again a year later...I went to the ER and they just gave me a prescription for pain and Penicillin.This is the tooth on top next to the very front tooth on my left side, and it started giving me sinus problems, like felt weird in my nostril and pressure and pain in sinus. About 5 days later I went to dentist and he said I still had alot of infection in tooth. and I told him about the sinus problems and he said it was infection..He gave me another antibiotic to go along with the penicillin, ok well after that 3 days later I get my tooth extracted, very painful...He told me 2 days after the extraction I could stop antibiotics, So I did, because it was causing severe diarrhea and he told me that anyway..Well it seems to healing fine and theres no drainage, but Im having the same sinus problems, like the gum feels stuffy and sinus pain, sore throat...and a little pain...and this extraction was done on tuesday and it friday...So could the infection still be there?? I dont understand why it would be after 2 antibiotics, but since he said that my sinus was hurting from infection, i started thinking maybe the infection is still there...Please help!!!