I Have Had A Sore In My Nose The Past

I have had a sore in my nose the past two months. Last week my doctor put me on 500mg of cephalexin four times a day. It seems to be getting better. Yesterday a red dot a little bigger than an eraser appeared on my calf. I have been pretty warn down but I think a lot of it has to do with my job. Could this be a staph infection????