I'm obviously not a doctor and it is impossible to say what you have over the internet.

However, I did have ITBS once and actually, it was from one thing above all others......too low a seat height. One thing I noticed about having it, was that climbing stairs was painful/tender. Perhaps your symptoms are different.

Anyway, I would raise the seat up until the point where you start bouncing in the saddle when pedaling. Then from that point, I'd lower it just enough to eliminate the movement and no more.