My 10 Year Old Son Was Treated For Strep Throat

My 10 year old son was treated for strep throat 12 days ago. He completed Amoxicillin 1000mg PO Qday 2 days ago. Today he is running a low grade fever 100.4 and complaining of a sore throat again. The clinic is closed until Monday. Do you think I should wait until Monday to see if he's feeling better, or call the on call MD? He was symptom free on day 2 of the antibiotics originally.
Thank you,
Nurse Mom