Hi I m a sixteen year old female. The fifteenth of November I had unprotected sex. My period came six days later, it was on time and completely normal. Two weeks ago I had protected sex with the same person. On Thursday morning my period came eight days early. It was very heavy and I had terrible cramping but only lasted two days, but my period has always been six days ever since I got it four years ago. The next morning I only had very light spotting when I first woke up and it was light pink in color. There was no bleeding for the rest of the day. Today I had absolutely no bleeding until half an hour ago when I found a small amount of brown thick discharge. When I wiped again there was a very, very small amount of very light pink discharge that seemed watered down. I m also having very bad pain in my lower back. Nothing like this has ever happened to me and I m sick with worry. What could this possibly be? Do I have an STD or something?