Stomach bloating and no clue what to do

[Ally_Moore]

I have recently noticed that my stomach, just in a circle around my belly button and up the center of my body( from belly button to the beginning of the middle of my ribs) has been  bloated or swollen. It doesn't really cause any pain, and I'm not on my period. I'm 15 years old and I eat decently healthy and get moderate exercise, like walking around school all day, orchestra, and running sometimes as well as gym class and stretching almost every day. I'm very concerned about this and I weigh around 86 pounds. I am a skinny person so it very clear that my stomach is a little larger. I don't have a clue what it could be and there is no way that it's possible I could be pregnant or anything like that. I tried asking my parents but they think I'm "messed up" because I read about a lot of medical disease and things online and talk about it. I can't pinpoint the cause of this, but when I noticed it, I instantly began to eat healthier than I already do, and a lot less. Please help me, I have no clue