Clicking is normal a tendon snapping, could be down to tight hip flexors if its when you extend your leg or as you say a tight IT band. A sports massage might help and identify the tight areas so you can do the right stretches.
I'm battling with it too at the moment probably down to increasing my miles for the GNR.I have seen a sports physio who has been doing ultrasound which has helped and allowed me to continue running. He also advised loads of calf stretches and icing.
I have dysplastic hips so have had loads of surgeries including two to realign my pelvis hopefully to slow down the progression of arthritis. I have moderate arthritis in both hips and one will probably need a replacement by the time I am 50- in five yrs time. I figure as its pretty much inevitable anyway,and I wont be able to run then so might as well do it whilst I can (with my consultants permission). Sometimes I need to take extra rest days, and I see a sports therapist once a month for massage to iron out muscle imbalances etc but can manage about 25 miles a week quite easily. I can do up to half marathons but think I would struggle with the demands of a full. Hope this helps.
A Labral tear can be diagnosed with an MRA ( MRI with a contrast dye) has this been suggested to you? Also I would ask your OS if they have ruled out FAI as this can be an underlying factor to a tear and often causes the posterior symptoms that you describe. No amount of PT will cure a labral tear, it would need an arthroscopy.
Good luck I hope you find an answer soon, after 5 years of dealing with complicated hips and 6 surgeries I know how frustrating it is.