My anus itches. i have anal mucus. i get nauseous twice a week. my feces are inconsistent shapes. my weight is fluctuations rapidly. acid reflux?

Proctocolitis?: Acid reflux has nothing to do with this. Sounds like rectal or colon inflammation (proctocolitis). Maybe worse-than-usual irritable bowel syndrome, but it's also possible you have inflammatory bowel disease (Crohn's disease, ulcerative colitis), celiac disease, or other serious intestinal problem. If you're gay and have had anal sex, STDs are possible. See your doctor or a gastroenterologist soon.