Suggest Medication For Severe Cold, Asthma And Nasal Congestion In A Teenager

My 15-year old son has a severe head cold causing his asthma to flare. He has severe nasal congestion. No fever. We tried Allegra D-12 BID for 20 days and no luck. Nasal sprays make him even more congested. Would an antibiotic help, if so, which one. I was thinking a round of amoxicillin and a medrol dose pack. He is already taking his albuterol breathing machine every 3 hrs. I work for a dr so I am able to call in his medications. my email is YYYY@YYYY