Constant cough. With this from 2 years.

Hello.my kid has wet cough from last 5 weeks he got viral fever ,fever got reduced but cold nd cough is still there again he got viral fever last week, he got allergies to ,he coughs a lot at night or early morning and vomits phelgm daily and sneezing and nose block daily,and any seasonal changes he gets cold nd cough immediately and sometimes fever too .we took him to pulmonologist and prescribed some blood test ,which is Immunoglobulin IgE and it's results were very high 411.75KIU/L.he prescribed some medicine ,am really concerned because we are using lot of medicines for 5 years old.doctor saying it will affect his growth if we don't take care of his allergies or use medicine.but am really concerned to use this many medicines.can any one suggest best procedure or alternative as we are dealing with this from 2 years .his immunity also decreasing because of frequent fevers ,and cold nd cough daily which effecting his daily activities as well