I gave myself a mild case of this doing very wide stance squats very heavy twice a week for a long time. Do soft tissue work on your IT band. It will hurt, but roll it out good a couple times a week on something hard like a metal tube or pvc pipe. When that thing gets tight in crushes lots of stuff beneath it including that bursa in between it and the greater(?) tronchanter.
I also did alot of hamstring mobilizing work and rolled my tensor fascia latae on a solid ball at that time. This wasnt directly for the bursitus but I can't say it didnt help either.
The longer and heavier you are lifting random things like this will manifest, and its kind of a learning experience to identify and fix the underlying cause. More often than not something isnt moving as it should, and soft tissue work becomes routine maintenance.