Had mild-ish Pneumonia last week (bad cough, chills, 103 fever, weakness, etc) - got it confirmed by a doctor and chest x-ray. I got antibiotics fairly quickly, and finished my 5-day dose on Friday, and my cough cleared up by then. Today, though, it's suddenly back, and it's pretty bad. Should I be concerned? Do I need to go back to the doctor? I feel ok besides the cough, I'm just worried. Thanks!