I am a 21 year old female. I don't take any meds. About 3-4 days ago, i had an itch in my butt crack, I looked in the mirror to see what was causing it and i had a rash that started. Over the past couple of days, the rash had moved to all over my butt and almost to my vagina and upper thighs. It also started to form on my back and my elbow/arm and back of neck. The rash seems to develop fast and itches like crazy. It starts as little red pimply bumps that have space between the bumps, then after awhile it worsens and looks like a red, swollen mess, and the bumps run together. I had unprotected sex about a month ago. I'm not sure whether it's an std or not considering it started on my butt and im just now getting a rash. I also have a stomch ache, and feel a little light headed and confused. I got the rash a day after my mentrual cycle, don't know if that has any revelance. I sleep with my one-year-old daughter in the same bed and she has absolutely no rash on her. I don't have time to see a doc, i work and my husband is overseas....that's why i need to find out what it is (i.e. adulterous sexual encounter). Please help!!!! It's spreading really fast and it itches. It itches during the day and night and im losing sleep over it. It burns and almost feels like slivers under the skin.