I fell on stone steps and scraped up my knee and bruised my shin. the scrape is healing fine, but cellulitis developed on the bruise. I went to the dr.twice. first time they gave me cephalxin-no better, went back now they give me augmentin - harsh. nobody can explain how I got an infection when there was no opening in the skin. my leg is painful and ugly and I feel a little freaked. I wish I understood what was happening and why? help?