Thank you for your question.
It is possible to have local tissue infection with a normal blood count, also if an infection is partially treated with an antibiotic this can happen. Firstly I suggest that your doctor do a pus swab from the area that the tooth was extracted and sent for microscopy and culture as well as a sensitivity test for antibiotics. Secondly it is a good idea to cover for anaerobes growth by adding Metronidazole
to your treatment. I trust this helps you.