I think I "did" something when I ran my one and only parkrun in the summer. I have had niggling pain in my hip ever since. I don't remember doing anything but its a short course with tight turns and people, pushchairs and dogs stopping unexpectedly in front of you. Its some kind of muscle pull and I've carried on running and steadily increasing my distances. Had enough of it now though. Day after each run I hobble if I sit down for any length of time. I've just run a steady 4k and there is a faint twinge and tightening of muscles from my waist to my knee. I do not want to stop running but I am going to forget doing 10k in December to avoid overdoing things. Short and as level as possible slow runs, ideally three times a week. Ice, tennis ball and roller when I get back and no sulking! Does this sound sensible to you all? (Internet diagnosis *rolls eyes*. Its not really, its moral support! )
Edited! I had completely forgotten that other people go through this - lots of useful posts. I shall gently try some of the stretches people are recommending!