The amoxy was 500 mg - once per day?
That would be a very very low dose - may have stirred something up though.
Here's an excerpt from the ILADS Guidelines regarding tick bite treatment (when no EM or other symptoms have arisen)
TREATMENT CATEGORIES
PROPHYLAXIS of high risk groups- education and preventive measures. Antibiotics are not given.
TICK BITES - Embedded Deer Tick With No Signs or Symptoms of Lyme (see appendix):
Decide to treat based on the type of tick, whether it came from an endemic area, how it was removed,
and length of attachment (anecdotally, as little as four hours of attachment can transmit pathogens). The risk of transmission is greater if the tick is engorged, or of it was removed improperly allowing the tick's contents to spill into the bite wound. High-risk bites are treated as follows (remember the possibility of co-infection!):
1) Adults: Oral therapy for 28 days.
2) Pregnancy: Amoxicillin 1000 mg q6h for 6 weeks. Test for Babesia, Bartonella and Ehrlichia.
Alternative: Cefuroxime axetil 1000 mg q12h for 6 weeks. 3) Young Children: Oral therapy for 28 days.
www.ilads.org/lyme/B_guidelines_12_17_08.pdf