Abcessed tooth pulled now severe headaches wasnt given antibiotics?

My husband got his tooth pulled a couple of months ago. Dentist told him it was a bad abcess and pulled it. Didnt give him anything for it! Couple of days later pain starting radiating up his neck and all around his head. He now has a constant HA that wont go away and sometimes its so bad that it makes him sick! Hes had bloodwork, ct scan and mri! All negative..I keep thinking it could have something to do with his tooth he got pulled and infection?! Am I right?!