Saddest aviator
I went through the same thing in the late 80s.
I was one of the highest remunerated FOs in the industry but had to work for it.
It started with a weird lung infection probably from West Africa which depleted my immune system. Eight years later I had my first 3 month sick leave after catching malaria.
I applied for a flight ops position with the CAA but didn't even get an application form although I had many times more experience than others I knew were in the job. A former colleague said I was a fool as I should have known that it was for masons and guild members. I don't dispute his reasoning.
After a couple more years and a second bout of malaira I developed ME although it was a disease for weirdos and malingerers at the time.
I was already on a special roster avoiding Africa but fortunately flew with our chief training captain who recognised the symptoms and he got me a transfer to short range.
My health improved and I looked at getting out of the profession but faced with a very substantial loss of earnings and an expensive family I decided to take a couple of months unpaid leave each year.
After my command my health improved somewhat as the job was much easier than as a first officer.
18 months later I had a head injury which gave me memory/sight and hearing problems. A week later a friend topped himself whilst I was waiting for him and I started on the depression slippery slope.
I got screwed by my chief pilot (brit a@@@@@e) and found myself waiting for a bus course which I didn't have the confidence to start.
I was forced to take an extremely good loss of license package but missed flying.
Gliding/paragliding/instructing and a good wife and friends helped a great deal.
I completed a weeks course with Paul Mckenna on NLP - it changed my life.
I cannot quantify your problems but the cumulative affects of being locked up in an aluminum tube, breathing C@@p air, working odd hours plus the occasional stress factors ain't good for man nor beast.
I would suggest that rather than walking away from the career that you get help (BALPA?) to see what you can change to improve the quality of your life.
There are many routes and I have seen friends with worse problems than mine take different directions - one went into management and wrote his own rosters and another went to the funny farm.
good luck