What do you think i did to my knee? please answer asap!!!!?

heyy(: i hurt my knee in gymnastics on wedensday and its still bothereing me i have a brace on my knee and everything and ive been icing it. My knee is a little swollen but not to much. When i turn it right/left it make like a cracking or popping sound. This is what i noticed the most and bothered me the most. It hurts (out of 10) a 6sometimes 7 or 8. It mostly hurts when i turn it and go up and down stairs. It gets very stiff when i dont move it for even a little while. It buckles a little bit when i walk on it. On my knee there are two areas on the side of my knee which is swolen and it hurts. I did some research and i think i might have torn my ACL. all the symptions are the same that i have. Im only 13 and im a gymnast and im scared of what might happen. please tell me what i should do and what might be the problem. btw the knee that i hurt was also my weak knee because i sprained it like when i was 8ish. thank you soo much!!!!=)