Suggest Treatment For Impetigo

hi my 4 years old son was suffering from Impetigo. Doctor prescribed him Roxid (roxithromycin oral suspension) from last 5 days he is taking this medicine.Yesterday I have noticed swelling and rashes on his face. today morning swelling increased and face was red. doctor is saying it is allergy. but not able to tell from what? still she is asking to continue the medicine. I have read on the net rashes are uncommon side effect of the given medicine. pls advice whether i should continue the medicine?