Was diagnosed with bronchitis 10 days ago. took antibiotics as doctor said and i felt better. now my cough came back again. worried about pneumonia!

Viral. Abx do zilch: You probably had a viral bronchitis, especially if you did not have all of the classic signs. Antibiotics do nothing for viral illnesses. Viral illnesses go away in about 7-10 days but can come back if you get re-exposed to a different virus or a different strain of the same virus. Did you get a flu vaccine last year? While 85+% effective, some strains 'slip through' the vaccine protective net.