I'm sorry to hear so many suffering with IT Band Syndrome. I'm going to offer a single post on the subject, as it's unfortunately something with which I'm all too familiar.
My background: it nailed me training for my first long distance race, 2012 TOT. I tried to push through and made things MUCH worse. Like, unable to run more than a 1/4 mile worse. Took weeks off, foam rolled, did the stretches and strength work indicated when one Googles ITBS. Walked most of 2013 PHM, but finished without issue. Nailed by it again at mile 10 of 2014 WDW Half. Worked with a chiropractor to really nail down what was my root cause, rested, rehabbed, changed what needed changing, and I've raced TOT, W&D and a local half with no sign of ITBS. So what did I learn?
1. You MUST rest it. Completely. That knee pain is caused by inflammation and until you allow that inflammation to go down completely, you can't do anything; it'll just keep getting re-irritated. A few weeks of no running should do it.
2. Spend that rest period figuring out what's causing it. This is HARD - there are a gazillion things that can bring on ITBS. Your best bet is finding a doc or chiro who understands running mechanics and can help you rule stuff out. Contrary to popular belief, it's
not always weak or unbalanced muscles . In my case it wound up being the wrong shoes mixed with very steeply cambered roads, which put my foot into a weird position, creating tension from the bottom up, not the top down, as is so often the case. But maybe your issue is with muscle weakness or imbalance - you need to ID
which muscle/s and the best exercise/s to correct that.
3. Come back s l o w l y. Half a mile to start and build slowly from there. I found I did best with low mileage, but frequent runs; 2 days running, 1 day doing something else. I was able to build back up pretty quickly, but not in big leaps.
4. Foam roll... but in the right way! Google this one and spend some time getting to know your muscles. Just rolling around a bit won't cut it; you need to get the right spot/s in the right way/s.
Everything else is very much individualized. I like yoga and have been practicing for 20+ years; I think it probably helps keep ITBS at bay, but I wouldn't go so far as to say it's a magic cure. Newton running shoes were a near-instant solution for me, but only because they happen to be the brand that best works with my personal mechanics. Seeing my chiro was a big help in IDing the problem and healing the inflammation, but an ortho or PT who knew how to do the same would have been just as helpful. ITBS is an absolute beast that requires a lot of time and attention to figure out, and really, a lot of experimentation to see what works for
you. I dearly wish there was some magic solution for it, but there just isn't.
Sending best wishes and healing thoughts to all suffering with it - I KNOW your pain and hope you never have it again!