I have had ITB issues on and off this year. I saw my physio on Monday and this is how things sit for me:
I overpronate on both feet. I also have glutes (GMed) which don't fire correctly. GMed deals with rotation whereas ITB and connected muscles are stabilisers - in the absence of Gmed handling the rotation ITB etc is forced to compensate and as a result this whole chain becomes tight and leads to the symptons you are experiencing. As a result my knees track inward slightly - this then affects my hips and then lower back. As a result my hips appear to not be level - a different physio suggested a couple of weeks ago that I had a leg length discrepancy. My physio this week performed some 'back cracking' and immediately managed to level out my hips. Coupled with some focused massage on my back this appears to have done wonders. I have a set of exercises to do to ensure Gmed fires correctly and is strengthened.
Interestingly I do bikefitting at a low level and have started experimenting with the wedges that I think DarkSpeedWorks was recommending. I have two cleat wedges under each foot - I discussed this with my physio and he thought it was an excellent idea.
I think all the changes to seat height and crank length etc may be missing the mark - they are dealing with the symptoms rather than the cause (and in the case of leg length discrepancy possibly missing the mark completely).
Get a physical assessment along the lines of what I have identified above.....
Where are you (the OP) based? If you're in Aus I can recommend a physio in pretty much all the capital cities.