How to stop being scared?

I will try to make this short.

Well, I am 18 years old (male) and I have a constant fear of change. Something simple like somebody knocking at my door, getting a notification on Facebook, my phone ringing or getting an e-mail, my heart starts racing and I start to shake really bad. I always shake no matter what is going on, I could be talking to one of my friends and I might hand them something or a simple hand shake and I get that feeling as if I was going to fall back to the ground. This also is one of the reasons why I quit school at the age of sixteen. When I would walk into a classroom or my name would be called by a teacher it felt as if I could not stand up from the chair that I was sitting in.

I don't have trouble meeting people. I am a very social person.

You might be thinking that I am a scrawny kid but I am not, most people I know think that I am the type of person that loves to have attention.

I am 6' 1 and weigh roughly 220

And yes I do lift "bro" I bench 185 and adding more each day

I use to play soccer and football in middle school till 10th grade