My baby's first tooth appeared a few days before his 4 month checkup. His pediatrician was surprised, but not concerned. He (my baby, not the pediatrician!) had been very drooly and occasionally fussy for a few weeks prior, and bibs were a regular accessory to his wardrobe, sometimes needing a fresh one 2-3 times a day! He's got 8 teeth now, but they're not all the way in yet. Hang in there - and don't feel bad about using Tylenol, you're helping relieve his pain!