I've got CRPS, complex regional pain syndrome. It used to be called RSD, but I wouldn't be at all surprised if you hadn't heard of it; most doctors, GPs anyway, haven't either. It took about a year and a half to finally get diagnosed. It's like the most intermittent, spooky fault you can imagine, affecting every system but in hard to identify ways.
I got lucky, relatively, in the end and saw a rheumatologist who had previous experience of the condition and she confirmed it with a three phase bone scan which showed the pitting in the bone which is apparently a dead giveaway. Even then, as there is no cure and not much that can be done to mitigate the condition once three months have passed the specialists sort of.... gave up and palmed me of on to clueless GPs who have just kept handing out the opiates.
So, to finally make a point, no, I don't have much luck dealing with the medical profession, although I kind of get why. Who would want to spend much time on an aspect of their job which they can do nothing much about? It would be like keeping a shitty old scope barely going by changing the fuse and filter caps every week, while never being able to fix the part which is actually causing all the problems, like an obsolete proprietary ASIC. How long would it take to get bored of that? Any sane person would ditch the 'scope.
As for GPs, bugger their luck, too. Mostly, they do a cracking job working out which of a million or so potential problems is afflicting you and getting you in touch with someone who can fix it.