I had some trouble with my ITB a few years ago and need a few weeks off before I was feeling 100%. In that time I did some exercises with residence bands aimed at strengthening my hips. I want to say my issues popped up right before a race too, and if memory serves I brought a compression sleeve with me that I put on my knee about 10 miles in. It helped with the pain a bit and I finished a half marathon fine that way but probably an ill advised play in the long run. Since that’s actually awful advice I should also say take the time you need to recover 😉

Best of luck with the race, let us know how it goes!!