I have mucus in my chest and when i tap my back and cough i spit up brown mucus ?

Bronchitis: You either have bronchitis or pneumonia, which is a radiologic diagnosis. Either way you have a bacterial bronchial infection, and with brown sputum, my recommendation would be definitely to treat with a prescription antibiotic. Some physicians may prefer to due a sputum culture prior to initiation of therapy. You need to see a physician, and of course consider smoking cessation if you do.