Maybe it is about to personal character and habit. Some people would roll eye balls as they are nervous or feel uncomfortable. Try to take ease and deep breath while you are nervous. Ask your friends to remind you while rolling eyes.
If your eyes feel uncomfortable, let your doctor know and he will tell you how to deal with.
Well, in my opinion, it might be the eye irritation which leads to your rolling frequently. As we know that when your eyes are invaded by some irritants, or some virus, it can just make your eyes irritated. At that moment, it will just make your eye itchy. And of course, you will have to roll them frequently. So just stop rolling your eyes. And go and see the eye doctor. Maybe he will give some eye exam. And then some medical care will be necessary.