pneumonia
"After what started out as "hay fever" and quickly escalated into a head cold, then severe lung infection including shortness of breath and the inability to expel the phlegm I went to urgent care. 
They prescribed azithromycin  (500 mg followed by 4 doses of 250 mg) it took 3 days before I started to feel relief. I was feeling very sceptical until I got up this morning With only one more day worth of the medicine I can honestly say I think this stuff is great."