Could Cough In An Infant Be Due To Antibiotics?

My four month old went to the doctor for a regular check up on Tuesday. We were told he has an ear infection and he was put on antibiotics. Antibiotics always seem to make my children sicker. Its Saturday and now he has a runny nose and cough. The cough worries me because it sounds like he is straining. Should i schedule another visit and should we consider not using antibiotics at all?