I am having a terrible burning in my stomach, up into my chest and I feel like I have a lot of gas. I don’t have to eat very much food before I feel full. Sometimes I get nauseated and I vomit. What is wrong with me…?

I have been playing volleyball and walking /running lately. My ankles, knees and hips usually start to hurt after participating in these activities. What could cause that at the age of 22?