I Have Had Loose Stool, Sometimes Watery, Since Thanksgiving. My

I have had loose stool, sometimes watery, since Thanksgiving. My dr. Has done lab work for C-diff, & 2 different stool cultures & everything has come back normal. I have "episodes" about 5 times a day w/ cramping & bloating. I am slowly loosing weight (about 4-5 lbs. so far) . I ha e also started having an "episode" during the night & have to wake up & deal with it. I am getting frustrated, assume I am not contagious, and getting worse, not better.