Knee Injury

So, I was training the other day in Jits class and I got caught in a knee bar. I didn't tap like an idiot and I thought I could somehow turn it into an arm bar. Didn't happen and when the round was over, I could hardly walk. I've never had any severe knee injury before, but now it feels like there's something wrong. It's gradually getting better but whenever I put ice on it it kills me, that's how I figure something is wrong. I hope it's just hyperextended but I just wanted to get some thoughts. I'm trying to stay away from the doctor for the time being.