How To Treat Knee Pain And Cracking Caused Due To A Injury?

Hi, I had an accident during skiing. I am 22 year old male, fit. I have hurt my knee, and I was wondering if it will require MRI. I have not heared the pop sound in my knee, but I believe I have stretched my ligaments. I have not had a bruise for the past 20 hours, only in the last 4 hours slight brushing has shown. Knee is okay, the only problem are ligaments, the ones under the knee.