That sounds like a regular presentation of an abscess, but yes also could be pulpitis. Have you seen a dentist or endodontist yet to have it addressed? The root areas of our teeth seal themselves off pretty well, so regular systemic oral antibiotics sometimes can't help with dental infections, and they need to be cleaned out directly and/or injected directly with antibiotics. It's most likely a coincidence with regard to the Lyme, but regardless I'd strongly recommend heading to a dental professional ASAP so you don't lose the tooth!