I would suggest that you start with an overhead squat assessment and see what other muscles may be compensating also as it is rare to have just 1 muscle/tendon cause all the issue.
However, for the IT band I use foam rolling. Look for a video by Eric Beard on youtube about it. He is amazing – teaches for NASM, years of hands on experience, etc. You may also want to “look up and look down” at muscles at the hip and in the lower leg which may be causing the IT Band to get “tight” as it compensates for other muscles not doing their job.