I agree you should talk to your doctor. When you get this way is it high anxiety? I remember when I was taking that med that gave me sever panic attacks my entire body would stiffen up. I would have to grip onto something and stretch my arms and legs out straight as waves of panic washed over me, and it felt like my entire body was freezing. I couldn't explain it. Even when I was not having these I was always tapping my feet or fidgeting. At first I didn't even think it was the med since I had so much other emotion stress in my life at that time, but after about two weeks I looked it up and sure enough, panic attacks was a side effect. I went straight to my doctor, (even though he was an OB GYN he took me right off of it.) Well, after about a week those went away. So, talk to your doctor ASAP. You don't need to live with that if they can figure out what is causing it.
This is something of concern and you should speak to your psychiatrist about it and see what they can do to stop it and see what the cause is.