Why do I feel sick/nervous around people/my friends?

I'm always so nervous around people if I'm going to hang out with them or w/e. Even with people I've been friends with for forever. I feel like my life's going out of control like I can't handle anything. I feel slightly more comfortable with my mom there but still shake and feel sick to my stomach. No individual thoughts come to my head and I can't really point out one thing that makes me nervous. I know I can't really eat when with people or out [either don't feel hungry b/c I'm nauseated or the thought of food makes me nauseated]. idk if I get car sick or not but I was driving to a concert yesterday and it took about an hour or so to get there and I felt so sick I couldn't stand it. and when I woke up the next morning I feltl ike that too [my friend slept over]. I never do actually throw up though. I get like this with everyone who isn't in my immediate family. Friends I've known for years or someone new I meet; guys/girls doesn't matter. I was homeschooled for 2 years because of a stomach condition that I had, but that has since been resolved from getting my gallbladder removed. I'm terrified for school next year - what if I can't handle it? I'm 17, I'll be a senior. PLEASE help me