My Son Has Been On Two Different Anitibotics Over The

My son has been on two different anitibotics over the last month and still is complaining that he is coughing/throwing up mucus that is making his stomach uneasy. Any suggestions on what we need to do? initial diagnosis was sinus infection...he also has allergies and asthma and takes a daily dose of zyrtec and singular along with this advair inhaler..any suggestions would be welcomed..