My Five Year Old Son Was Treated For Bronchitis Last

my five year old son was treated for bronchitis last week and now has a lower eye, maybe sinus cavity that is swelling from time to time. His eye itself is not red but the eye duct does secrete a small amount of pus. He doesn't like to blow his nose and I have been catching him 'drawing' back most mucus that should be blown out. Could this be a sinus infection? He was put on a z pac... he is now off of antibiotics. Just concerned because the lower 'eye' socket keeps swelling.