I am in no way a medical professional, but I have a port wine stain that covers the whole right side of my face. I am 35 and have had sinus infections and ear infections all my life. I now have gluacoma in that eye. As I get older the sinus infections seem to get worse and I have been told by my doctors that there is nothing I can do because I have bad drainage.
Anyway...I was allergic to penicillin when I was young. I would get an red itchy rash. I can take them now so your son might grow out of it.