I used to be an avid runner running about 25 miles a week. I started getting pain in my calf after running that was bad enough to make me limp. I went to my doctor who sent me to physical therapy who attributed it to arch supports in my shoes. After using the new arch supports the pain in my calf disappeared but moved to the center of my hamstrings up to my glutes. I wouldn't hurt while running just every other time. It would be a particular problem when driving. I would get leg cramps so bad I would have to pull over and stretch it out. Putting a can or ball under my leg helped but didn't completely take care of the problem. I went to orthopedists, physical therapists and even chiropractors. Tried stretches, exercises and even a lift in one shoe and nothing. I eventually stopped running altogether and the pain eventually went away. I miss running and decided to try to start again a little here and there. After a 2 mile run this morning I can already feel a hint of the start of the familiar pain in my glutes. Does anyone have any suggestions?
I had a lot of hamstring, hip, and glute pain back when I used to run on roads, and like you, the pain would become almost unbareable when driving anything more than a few miles. I discovered that a combination of running on dirt trails and slowing down and doing more miles has allowed me to continue running almost pain free.
Don't know if running in the dirt will help you, but you might want to give it a try.