My ankles hurt from running on uneven terrain?

I am used to running on the track. I've just now started to do cross country and the uneven terrain is driving me crazy! As soon as I get into a rhythm all the sudden one of my feet is in a ditch and twists. This happens constantly and I want to know how to stop it. I was thinking about investing in some trail running shoes. Right now I'm using Adidas Supernova Cushion 7 which I know is more of a road shoe, but they are also pretty shot, so I don't know If I could just get another road shoe because I like the lighter weight.