It was in fact NOT an STD - it was a skin infection caused by fungus. They kept me in the hospital for a week to monitor me and gave me Antibiotics by IV, as well as oral Antibiotics (Griseofulvin, Bactrim) and anti-fungal cream & shampoo (Ketoconazole, AmLactin, Nizoral) to treat it. They were trying to figure out where I got it, because they said infections like that are usually picked up in hospitals.
In response to your statement of "Why don't I start using condoms", I DO use condoms. But everyone knows (or at least they should know) that not every disease or infection is caused by sex. There's a whole slew of STD's and other stuff you can get simply by skin-to-skin contact.