Re: It might get better eventually
Sounds like you are no closer to a diagnosis than before, but maybe some things have been ruled out? I agree that taking NSAIDs for ?no apparent reason? isn't really fixing the problem, particularly because they don't help! No need to create more problems from side effects.
Have any of your X-rays been load-bearing, i.e, standing x-rays? Did any of your X-rays or MRIs reports note anything of significance? If they don't, getting a second opinion on the films might be helpful: I have an operation report which notes no evidence of impingement in my hip; a more specialized surgeon, looking at just plain X-rays, was able to locate the impingement. There's a great hip surgeon in Nashville, named Thomas Byrd, who will perform a file review to determine if there's anything he can do surgically to help you. I contacted his office, but ended up locating a specialist closer to me.
I hope that your GP is tracking your progress; if not, I would recommend returning to the GP to ask for help in locating the correct type of specialists and evaluating the feedback you received. Going to a university hospital could be a great idea, if that is an option for you. You might also ask your GP about going to either a sports medicine orthopedic surgeon (they do very little surgery) or a physiatrist.