This is a manifestation of late disseminated Lyme disease
Doxycycline 4.4 mg/kg/24h PO divided q12h
There are limited safety data on the use of doxycycline for > 21 days in children < 8 years of age
Amoxicillin 50 mg/kg/24h PO divided q8h
Maximum: 1.5 gram/24h
Cefuroxime 30 mg/kg/24h PO divided q12h
Maximum: 1 gram /24h
Azithromycin 10 mg/kg/day PO once daily but this is considered second or third line therapy as it is considered less efficacious.