So in gym class we had to run for 12min and I did 2.3km during that time. At the end I had a really bad cramp, but when she said 1min left, I still sprinted during the hole time. At the end I had a HUGE cramp.. But now around 3 days later, it still hurts at the same spot :/ but less intense. Like it hurts a bit, but it's still bothersome. Please help!
I had the same symptoms when I started running. Take a look at this article.
It could have a lot of different causes. But mine went away after these precautions:
I do not run with a full stomach or with a lot of fluids. Also I drink no more than a few sips during running. You can't breath well with a full stomach.
Also, I do start with a low pace and try to keep my breathing pattern when speeding up. If you pay attention to your breathing, you will breath much better.
Stretching obviously helps too. If you try these and it does not go away, I would suggest talking to a physician.