I am sorry to jump on this so late. I have this in my left knee exactly as you described it. It is spasticity. You need to talk to your doctor about it. There are several meds you can take for it. Baclofen is popular, it is a muscle relaxant that works through the spinal cord and so you don't have that fuzzy headed feeling. I don't take anything for my spasticity but I stretch constantly. My spasticity is more of an inconvienence, but it can be very painful for many. Take care.
love and prayers