Infant having constant ear infections with stuffiness. Had Zyrtec and cefrozil. What could be the underlying cause?

My 10 month old has constant ear infections. She is always stuffy. She is currently on day 7 of for a double ear infection, and 4 days before this course was on cefprozil (sp?) for another ear infection. After speaking to her Dr, we thought it is possible allergies could be an underlying cause of the constant congestion which in turn leads to the ear infections. 3 days ago I started her on 1/2 tsp a day of Zyrtec. She has since developed a wheezy cough . Could the Zyrtec cause a cough like this? I am concerned about continuing this drug if it is making her worse. Thank you for your help.