Did i tear my ACL in my knee?

I hurt myself at gymnastics and my knee has been bothering me since wedensday. At first i just thought i mite have over worked my knee because it has allways been weak. Now its saturday and its still hurting me. i have a knee brace on to stop the pain but it still hurts. It makes like a poping noise when i move it 2 the right or left i can also feel it. Its also stiff when i dont move it 4 a while.its a little swolen but ive put ice on it. it hurts most when im going up/down stairs and when i twist it right or left. it also hurts when i try to bend/straighten my knee. what do u think is wrong with my knee? thank you!! =)