Bad Fecal Odor

Hi, i'm 17 years old and around age 15 i started to notice I had fecal odor or as many people would say smelled like ass. I don't know what's wrong with me.. It only happens when I get nervous or anxious about something... It feels like my ass is sweating or something and then I smell really bad. I really would appreciate it if anyone who ever had the same problem to some extent had any advice? I don't know I think I might have IBS (irritable Bowel Movement) but i'm not sure. I'm just glad to know that I'm not the only one with this problem.