Yes, that sounds very familiar to me!I've found it can also be associated with hamstring and abductor strain. I thought for ages, based on online research, that I must have piriformis syndrome and tried all the exercises recommended for that condition, but without success. In the end a decent physiotherapist unpacked the suite of problems I'd developed and concentrated largely on the lower back as the principal cause. I was advised the mobilise the lower back muscles before every run. This is done by performing a kind of press-up with your hips left on the floor, and holding for 30-60 seconds.It helped me get back to running although I've found problems have recurred if I stop doing the stretch.I also think you might be helped by exercises to strengthen your hamstrings - runners and cyclists harbour the illusion that because they use their legs a lot their hams must be strong: wrong. Google 'posterior chain weakness'. Also, don't neglect hamstring/glute bridging exercises.Good luck, and please let me know if you find anything else that helps!