pain behind my knee

I’ve been practicing bikram for about 10 months, 4 times a week for the last 2-3 months. I’m not currently running or doing other exercises. I typically practice very early in the morning, but I usually spend at least 10 minutes in the hot room doing gentle stretches before class.

My legs and hamstrings have always been tight all over, but recently I’ve been developing a pain behind my left knee that gets worse as class goes on. (When I say back of the knee, I really do mean just behind the knee joint — no real pain going into the thigh or calf muscles.) The strange thing is that I can barely feel anything during the day in my normal life, walking, climbing stairs, kneeling down, etc. I’ve been trying very hard to negotiate the difference between discomfort (that I can breathe/work through) and pain (where I should back off), but it seems to be getting worse.

The discomfort starts in Standing Head to Knee pose when I balance on my left leg to kick out my right. I’ve talked to my teachers, and they’ve watched me to make sure I’m not jamming my knee back and that I’m locking my standing knee correctly. The discomfort gets a lot worse when I try to kick out the left leg, and I definitely can’t lock out the kicking leg.

In Standing Bow, I can feel it hurt when I’m standing on my left leg, and it feels so tight that it’s hard to come down parallel to the floor (which I can otherwise do), but I don’t feel it at all when my left leg is kicking. The same goes for Balancing Stick; I only feel it when I’m balancing on my left leg.

The only other two postures where it really bothers me are Standing Separate Leg Stretching (where I used to be able to touch my forehead to the floor with legs locked, but no longer), and Head to Knee pose. But by the time I get to the floor series, I can start to feel it pull and hurt on every sit up. I’ve tried working through it, I’ve tried easing off, I’ve asked all of my teachers to observe me, and I can’t seem to find a solution. One teacher suggested I try accupuncture, but before I embrace the needles, I would greatly appreciate any advice you can give me!

Rachel