Sounds to me like a patella tracking issue... I would have to give you an actual assessment in order to determine the underlying issue. However, most tracking issues are caused by weakness in the vastus medialis obliquus (lower portion of the inside quads), a tight iliotibial band (the part running from the knee up the 'outside' quads to the outside of the hip), and poor proprioception (a poor sense of how the body is positioned and what muscles are being used for certain activities).
I would recommend seeing a Sport's Physician, Physiotherapist, or Massage Therapist. If you can't afford either of these then here is my suggestion...
1) You need to strengthen your VMO. The exercises you use will depend on the severity of your condition. Different forms of weighted lunges and squats are the best way to build it up, but they would be best for someone a little further along in recovery. For the first month or so I would suggest Wall Sits (at varying angles) and One-legged Squats. g8r80 was right to say that cycling helps too, however, try not to use your momentum from the push off the right leg. Focus on feeling the left leg working each time you pedal. To really get the benefit of these exercises you need a qualified instructor to guide you through them. They may seem simple, but if your proprioception is a problem you will likely make the problem worse by performing the exercises incorrectly (even if you do it just like the picture/video).
2) You need to stretch your IT band. If I could post links I would hook you up with some stretches (I haven't reached my minimum post requirement yet).
3) Improve your proprioception. As part of your rehab, I would definitely get you working on a bosu ball and training towards using balance boards. Here is what a sample rehab routine would look like... All exercises would be done bilaterally (with both legs).
3x20s - IT Band Stretches
3x10 - One-legged Squats (3 sets per leg)
3x30s - Wall Sits: Each set at a different angle. I would go parallel to the ground, just above parallel, then about 45 degrees. It would help to place a basketball or something in between your legs as well.
3x30s - One-legged stance on a bosu (3 sets per leg)
3x30s - IT Band Stretches
I realize that most people don't have time to do this every day. Reduce the number of sets to shorten it up if you need to... Just remember that the less you do, the longer it will take to properly recover. The absolute least that you could do to help would be the IT Band stretches. 3 sets of 30 seconds 3 times a day. That's only 10 minutes a day of homecare.
Good luck!
Jon
