ITB is a bugger, but it’s fixable.
Foam roller/ rolling pin – lie on it so the painful thigh is on it, and move yourself so you roll up and down it. It’s a good way of massaging the muscle and loosening the knots.
Stretches: face a bed, pull your sore leg up, knee bent. Then lean onto it, so you’re stretching the outside of that thigh.
And strengthening: stand on the sore leg, with your other leg up (ie standing on one leg). Bend the knee you’re standing on, and slowly lower and raise yourself on it.
Do those every evening, regularly, and you should start to see some improvement in a couple of weeks or so.