Strange knee problem hindering stretching

[Behemoth]

I've had problems with my knees for years now, and no medical people have been able to explain them to my satisfaction. Essentially, whenever I'm moving into any position that you would expect to stretch the adductors, I get a pain and tightness on the outside of my knee - the IT band area, but just the knee. I often can't stretch to the point where my adductors would feel it - in the side splits for example - without my knees tightening up first and preventing me.

Any ideas whatsoever as to what's causing this would be much appreciated. It just doesn't make sense to me, that a stretch which should lessen any tension on the outside of my leg instead increases it.

[Fish Of Doom]

maybe it's... um... IT band tightness? :p (or maybe weakness in that range of motion)

do you have any pain when stretching your IT bands? how high can you hold a side leg raise?

[Behemoth]

I've never been able to get much of a stretch using IT band stretches, so I didn't think was too plausible. Plus it still doesn't make sense that a position which stretches the opposite side of my leg would tighten the outside of my knee (side splits, side leg raises, butterfly stretch etc).
And I can hold a side kick this high (http://i362.photobucket.com/albums/oo62/Jonathan_Slater/hillkick.jpg).

[Fish Of Doom]

actually it does make sense because you're contracting that area, but upon seeing the pic, it would not appear to be that, so no idea what it could be, sorry.