I had hip pain when my periformis was really tight, pretty common it seems. Its a large muscle across the buttock, joins spine to hip basically. It also can cause leg and knee pain. Mine was a comes and goes pain, sometimes really bad, sometimes nothing.
There are loads of good stretching exercises on you tube, they fixed mine in a few days
Also check out stretches for the psoas muscle, it’s on the front, either sides of your lower abdomen. Also causes leg and hip pain when tight – which it probably will be!