What Causes Electric Shock Like Sensation In The Knee Post Injury?

Hi I twisted my knee when I fell off my dozer in November I have been to a see a doctor and they feel that it is the meniscus. I have been to physio and doing the exersize they wanted me to do. But last night I got the weirdest feeling in my knee, it felt like an electrical shock going through my knee, and it is continuing off and on today. I was just why is that happening? I have never felt this before.