I have gone through similar experiences myself and am currently going through a similar experience right now. I wish I could just go into the doctors and ask them to run every test possible on me because I think I have X & Y but I know that's irrational and probably a huge waste of time for the doctors. At this point I just don't know what to do. On one hand I don't want to inconvenience the doctors more than I already have, but on the other I don't want to let any possible health issues go undiagnosed and possibly get worse if they go untreated. It sucks. It really really sucks. There hasn't even been a minute in the past few weeks where I haven't been worrying about my health. I get to work and all I can think about is getting home ASAP so I can be miserable there instead of at work. I try to play videogames or watch shows/movies to take my mind off of it but I keep reminding myself that I'm only watching those shows/movies or playing those games specifically to get my mind off of my health, which subsequently gets my mind back onto my health. It seems like it's a never-ending cycle.
I just wish I could get every test done, I really do. If there's some sort of full body scan or something I could get, I'd get it in a heartbeat. I just want to know if I'm healthy or not. I'm so sick of stressing out about this stuff.
So long story short, yes, I have dealt with undiagnosed health issues before, both mental and physical. It's tough. I got through it a few years ago when I convinced myself that I had every health issue under the sun, so I can get through it again, and so can you.
I wish you all the best.