Can Biaxin Pills, Cause Sore Throat Like Side Effects?

HI, My 5 year old son is on Biaxin for an eye infection. The eye has responded well to the treatment however he is getting sicker and sicker, he has a very sore throat,Fever of 103 Degrees, a cough that won't stop....do you have any ideas? Could he be allergic to the Biaxin? or could he have strep throat? Thanks Kelley