I still have a good amount left now, but my husband had something similar happen a few years ago. He got severely constipated and stopped eating much. I didn't notice at first because we were both so busy, but one day I saw he had almost no butt at all. He didn't mention the constipation, just said he was losing weight. I was so worried I got him a doctor's appointment, and they rushed him in. Turns out he'd lost about 30 pounds in two months. He finally admitted to the constipation then. He ended up getting a colonoscopy, and the day before he had to drink a huge bottle of laxative. Long story short, he was just really backed up. He gained the weight back and got his butt back too!