I Have A Small Rash On The Back Of My

I have a small rash on the back of my leg. Had it 4 weeks. Went to the dermatologist yesterday. She said it is viral. My other symptoms brought her to that. They are: last few weeks feeling lightheaded, some diarrhea on occasion, dry heaves or nausea. I want to know if I am contagious. About the same time all this started, I feel and hit the back of my head.