This started back in November. At first I thought I had gotten a std even though nothing was put in me and even assumed I have gotten HIV. But after a few test and research I put that thought aside. What happens is when I use the bathroom my stool either comes out a regular stool, broken up, or liquid like but becomes solid when I'm water. Also my stool began to float a lot more and if I haven't gone in a day my stool comes out a dark brown. Usually the whole time the color has been normal and I haven't seen any blood and have had no pain at all. Then usually when I go it either comes out kinda hard or soft and it usually depends on what I eat or drink the day before and at times certain food causes diarrhea. I even went to my doctor and they check it out and they said I was fine. Any idea on what this is?