I Fell A Couple Hours Ago Hurt My Left Knee.

I fell a couple hours ago hurt my left knee. When I try to put any weight on it it gives out & the knee joint goes 'inward' (towards the other knee). I don't have a lot of pain with it, but can tell if I twist my knee in the slightest. I have a elastic knee brace & ice on it. Do I need to see a Dr. ASAP, or should I wait a couple days?