Hi. I got a small bite of some sort on my lower leg. It developed quickly in to a large blister and turned black. I went to the hospital and they put me on a 2 g IV of flucloxacillin. Since then, although my leg is a little better, i developed a productive cough, aches, low grade fever, wheezing and a lump under my left arm. Im taking an oral course of flucloxacillin 2 g a day in four doses. My question is... why did i develop a chest infection after i started on the antibiotics? And why is it getting worse?