I'm 15 and I've recently changes classes, still in the same school same and all. Whenever I'm walking through halls and maybe even going to eat lunch with my friends I'm always shakey and feel nervous....and often get a butterfly in your stomach feeling. I've recently met this really nice cute girl and I was wondering if that was the problem..
It's been going on for 3-4 days now
I do have pretty stressful classes this semester

Changes in classes or school schedules is always a bit stressful. It takes a while to get used to things so do not worry if you already had a stressful semester. And never forget to reward yourself for having completed the stressful sem. If your problems persist, try to see the counsellor at school and address the issue. There is no reason to suffer unnecessarily. Best.