My 5 year old son was diagnosed with scarlet fever and strep throat. He was on penicillin for 10 days. This past week we took him back to the pediatrician and he still had strep. The doctor gave him Duracef, a stronger antibiotic. He has been running in an out of fever since then while he's been on this medication. How do we know if and when the strep will finally be out of his system? When should we seek further medical attention if he still gets a a fever in the next few days? Thanks.