How Should Recurrent Cold And Cough Be Treated?

My son is 1 yr 8 months old. He had severe cold and cough, and his paediatrician gave dose of monocef antibiotic and maxtra and relent. He was fine after a week but then it relapsed and this time the doc gave Allegra. He was ok in a week. Now again he has a flowing nose. Can I give maxtra and monocef? Or do I continue with Allegra?