Yes, I know there are a thousand knee pain threads out there, but each incident is unique and specific, so I'm "consulting the oracle" (as my girlfriend calls BF) to see if anyone's had the same problem, and what their diagnosis and/or treatment was. I'm trying to ask specific
questions (not "my knee hurts, why?") to get specific answers.

Yesterday I was at about mile 55 of a 63 mile ride and felt what I thought was a muscle spasm starting, tried to ride it out for a couple miles, then finally got off to stretch (haven't had to get off my bike to stretch in years). The pain is on the inside, toward the back of the knee, just medial to the big tendon behind the knee. After stretching the pain subsided, but returned in a less severe form near the end of my ride. Now the morning after it is still tender if I make a "cycling motion" but doesn't hurt to run or jump.

I ride a lot - about 150 miles a week, but have just began integrating longer rides over 50 miles for the first time this season. The research I've done points to tendonitis, which I know is common among runners, but I don't know about cyclists. Any shared experiences with tendonitis would be appreciated.

(And don't refer me to the countless "knee pain" threads that don't contain specific information, thanks!!) I have to abandon the thread for a couple hours due to work, but bear with me, as this really sucks!