Recurring knee pain from nearly 2-yr old climbing injury - looking for advice

I am a rock climber (bouldering specifically). Roughly 19 months ago I fell off the wall while attempting a dynamic move, landing with my left leg fully extended. There was a weird sensation when I fell, but I was able to keep climbing, walk home that night, etc... The next morning I woke up with very limited range of motion in my left leg, could not bend or fully extend it without sharp pain at the back of the knee, and it was a bit puffy at the back of the knee. After a couple weeks of rest and icing, it was noticeably better and I started climbing again, slowly, however the pain never fully went away and I found I was uncomfortable kneeling down, being on my feet for long periods of time, etc.. so i went to a doctor.

I've been back and forth to the doctor a number of times. First we suspected a popliteal tear or strain, however ultrasound ruled that out and I was sent to physio and given a number of exercises to work on strengthening the surrounding muscles. This definitely helped to correct my gait (as the pain caused me to develop a noticeable limp and significant muscle loss) and I was able to regain my range of motion, but still experienced pain upon kneeling/deep squatting. I was also given a prescription anti-inflammatory when the swelling did not go away after months, which did help reduce the swelling and improve range of motion. After a month or so, I went back to rock climbing, starting slowly, however after quite a few months I landed from coming off of the wall and felt the same sensation as with the original injury. Again, the next day there was swelling, my range of motion was limited and the pain was worse. Around this time I went back to the doctor and we scheduled an MRI, which I received in November 2016. The MRI ruled out a meniscal tear, which was another guess at what could be the problem and only showed "mild edema involving the inferior pole of the patella" and "trace amount of fluid within Baker's cyst". The previous ultrasound also showed the same Baker's cyst. At this point I was told it was "patellofemoral pain syndrome" caused by my knee cap tracking incorrectly and prescribe a "knee-o-trakker" brace. I wore the brace for a few months with no improvement. My physiotherapist did not agree with this diagnosis, but did not have any other ideas as to what could be the problem.

Following this I went back to doing physio semi-regularly (grad student without a lot of free time) and started climbing again. After a few months, the pain was much better, although still discomfort with walking or standing for long periods, and sharp pain when kneeling. Since then, I have experienced the same issue of landing while climbing and seeming to re-injure it, leading to a couple of weeks where it is difficult/painful to walk, and feeling like I am starting over. Each time, the swelling eventually subsides and it goes back to manageable pain/discomfort. I would really like to be able to get back to climbing regularly, however I'm finding that I am now fearful of falling at all, as even a good landing (knees bent) seems to trigger it sometimes, and that certain moves which require significant bending of the knee are no longer possible.

Looking for any suggestions as to what could be causing this, or what I should do next. I've run out of ideas, but really don't want to give up climbing :(