Could Knee Injury Be Related To LCL, While Having Swelling, Pain, And Squishy Feeling Around The Knee Cap?

My 14 year old daughter heard her knee pop during a basketball game. It hurt immediately but was able to finish game. Next day it was hurting and swollen. Every day it is getting worse. It locks up and catches on her. It hurts along the outside of her right knee, below her knee cap and behind her knee cap. Im thinking she did something to her LCL, but what else could it be? Her knee cap area feels squishy also.