I need help and advice

Hey everyone. So I'm in a bit of a pickle. After doing some research and looking at how other people describe anxiety and depression and taking those (I suppose weird) quizzes online, I feel like anxiety and depression could be a possibility for me, but I can't tell. I have this weird constant feeling in my chest, as if my heart is waiting for me to acknowledge the fact that it is always beating. It's not a pain and it's not the rapid beating that people get as a side effect from medicine. It's different. I am always afraid of what people think of me and I feel as if I am always having someone watch me. I realize that I carry myself as if people are actually there, judging me on everything I do. My emotions are so different, I can go from being happy (which does last for awhile) to feeling nothing to being upset and then eating too much to then go back to feeling like crap. I have realized that recently eating more and masturbating have become a way for me to momentarily feel better, but I always go back to feeling bad. I just don't understand this change in mood, am I too sensitive? and the feeling I always have in my chest, which is almost like a feeling of worry, but worry for something I can't explain. I have been scared to see a doctor about it because I play a sport, and I will be playing in college, and I don't want to ruin anything. Anyone have advice on what I should do? or what could possibly be my problem?