PT ladies -I have a question

I have noticed lately that I've been getting some ouchy areas. I try to stretch, and am pretty flexible (ballet in the past), but there is one very stubborn area that I just can't get relaxed; my right hip flexor. It doesn't bother me when I'm running, walking, or biking. About the only time I notice it is when I'm stretching, so I haven't been paying much attention to it. The other day, though, one of the sports medicine fellows was demonstrating a knee exam, using me as the subject - it didn't hurt my knee, but man did my right hip flexor protest with the movements.

Do any of you ladies have any suggestions? I don't want this to turn into a problem down the road. I am currently on anti-inflammatories (tendonitis in left ankle) and have iced it for the past 2 days. I've been doing some stretches (right leg behind and lunging on left, pulling right knee to chest and extending left leg while lying down, sitting on the floor with both legs turned out). I can feel it in the hip flexor during these exercises, but it just won't relax. I have full range of motion and no loss of strenght or numbness or tingling.

Anybody have any other ideas? Thanks girls!!