Sorry-ish for the long post…
I have had “ITB” type problems for years when running. I use speech marks, as I went to see about 4 different physios (might have been 5) over the years, they all had an opinion on the cause & all had different solutions to solve the problem. I am reluctant to call it ITBS specifically, even though all the symptoms point to it.
Nothing really worked to solve it.
The last time I attempted to solve it through healthcare routes, I had private healthcare so threw everything at it – consultation with a knee specialist (who apparently used to be part of the GB Olympic medical team), ultrasound, MRI, physio & gait analysis.
I did everything asked of me & that didn’t work. I basically gave up running as a result.
I can cycle for hours on multiple days & get no issues although the outside of my thighs going up into my hips always feel tight.
Several years ago I started doing yoga once a week at work. Once I got used to the moves, I started doing my own short stretching routine to target the area.
I do a combination of pigeon pose, piriformis stretch, happy baby pose as well as the traditional figure four stretch & a seated variation (no 4 here:)
https://www.medicalnewstoday.com/articles/325377#10-hip-stretches
I also started doing some exercises to strengthen my hamstrings and the muscles in the outside of my hip (adductors, or abductors I can never remember).
This made a massive difference & I went from being unable to run for 20 mins, to training for a half marathon. I didn’t get to run the half marathon in the end:
https://www.theguardian.com/uk-news/2019/oct/13/great-eastern-run-called-off-armed-police-response-peterborough
but ran an unplanned one about 6 months later on local roads.
I didn’t find foam rolling made much difference. It was the regular stretching that got me running again after struggling with this for years & years (~15 years I suppose).