Pain back of knee/top of calf when squatting

[alpha405]

For the last 5-6 months or so I've been dealing with pain in my left leg. It sorta creeped up on me. It started on the outside of my calf and now its in the back of my knee and the top of my calf. I'm currently going to physical therapy and I'm not sure if its helping. If I squat, do incredibly light leg ext's or any quad movement I get a weird pain in the back of my knee and the top of my calf. Its a weird pain and it feels like I have no power. The PT said I have a muscle in my leg thats turned off (i didnt know that was even possible) and I have a muscle imbalance in my quads (outer quads are stronger than inner quads and its making my patella track to the side). Has anyone ever dealt with anything like this before? I can train hamstrings and calves all day and there is zero pain. Any tips on making my inner quads stronger?

 

[alpha405]

Riding the bike also makes it hurt. I tried to do one leg squats where I put one leg behind me on a bench and squat with the other leg. When I put my left leg behind me on the bench and attempt to squat with my right leg, it especially sets off the pain in my left leg.