Low squat and hold for a minute. Feet a little open. That should remove the tension a bit. Look up stretching excercises for soas muscles. When it feels hams up to back, it’s commonly soas needs stretching. A good physio or osteopath (if not in North America as they don’t have them there) can help with a good stretch. It’s extremely overlooked muscle. Definitely high chance if you sit at computer a lot 

 I T band rubbed out with a rolling pin is good for knees, hams, soas.  

 Can you elaborate?