Why do I have such a bad fear of Rejection?

Since I started High School 2 years ago, I have had such a bad fear over rejection. I don't mean rejection by a girl saying "No" when i ask her out. I mean anything to do with Joining in on things. Like for example I get so much Anxiety that when I play a sport i fear so so much that I will drop the ball, miss the ball or failing. This happened once while playing football at school with my friends and a few people in my class, I had thrown the ball to no one while in a game I was so depressed that night. Well I'm depressed a lot but I try not to notice it and my parents don't care. Other times when i fear of rejection is when my brothers are playing together on the ground (kinda wrestling). I'll watch but I won't join because I think they will tell me to go away cause they don't wanna be near me. One more thing is that I NEED to have (be next to) friends because I think people will reject me because I'm different. I usually try fit in and act the way they act (people in my class) but I just end up acting like an idiot and making people not want to be near me. Is there something wrong with me? There had to… And if not, I don't know what to do.

-Sorry about grammar, am on iphone.

. I think you miss a lot of self-confidence, you don't have to think what others might think about you. The more you have fear of doing things the more might go wrong when you have the chance of doing it because than you have anxiety to do it.
Everybody is doing mistakes but won't get these feelings, because they know that this can happen, nobody is perfect, and this could be your problem. You want to be perfect without exercise and that makes you different and than people might avoid you a bit.
So don't care to much about making mistakes, nobody will reject you and if so than try to make it better next time. There wasn't any champion fallen just out of the sky and be No. 1, they all had to train before they got the Champ at all.

Thank you for your question!

About the fear of rejection. Keep in mind, that you can't please everyone and there will be inevitably be people who will dislike you. This is true for everyone because everyone has their own preferences. Some people like friendly people. Some like quiet people. Others prefer people good at sports. As we can't be everything to everyone, that means there will be people who will dislike you. Think about politicians. Many people do not like them and yet they can live with it. Politicians still have friends.

What is interesting, is that you are worried about what your peers think of you. The truth is that everyone worries about what other people think about them to a degree and the peers who you are worried about what they think about you, are worried about what other people think about them.