I Fell Out Of A Boat 2 Years Ago Into

I fell out of a boat 2 years ago into the water. I twisted my knee/body to try & catch myself. I've continued to have trouble with it. The pain isn't bad unless I exercise or walk. It feels like a pinched nerve or something of that nature because the longer I walk the more it hurts. The pain begins right below the knee & runs all the way to the top of my foot. It's like it gets stiff after I walk a little more than normal. To bend it up under me does not hurt or to straighten it out doesn't hurt but the in between movement/bending is terrible when it's locks up on me.