Hi, I can relate...
I've always loved working. Since I was 15 I worked a lot, and I put a lot of my self-worth into the quality of my work. When I was 26-ish (I'm 29 now) I landed a job that I LOVED. I learned a lot there, gained great experience for my resume, it paid well, they were going to pay for me to get certifications, and the company was flexible with things like me working from home if I need to. I was incredible thankful and happy where I was!
I've had severe Fibro and several other conditions my whole life, so I thought I had a handle on dealing & living with it. Well, about a year after starting this new job, my symptoms all started getting worse and I started getting completely NEW symptoms! It was scary! I went to Dr after Dr, continued trying drug after drug, treatment after treatment, but nothing worked and I was getting worse. The severe widespread pain in my body, chronic migraines, worsening photo-sensitivity, and the newest addition of constant 24/7 dizziness were making it impossible for me to work, even at home. I was terrified.
At that point I was taking a class at work to get a certification on top of my crazy workload. After hours of crying on my husband's shoulder, we decided that I need to stop the class. I wanted it so bad, and it was a great opportunity for my career, but physically I couldn't do it on top of work. It broke my heart. I told myself that once I got my health under control then I'll get the certification then.
Shortly before that though, I had sought out a local support group for Fibromyalgia because I was scared that soon I won't be able to function at all and that I'd have to stop working altogether. Well not even a week after leaving the certification class, I realized I couldn't work AT ALL, PERIOD. I went on unpaid medical leave, which is only 3 months. At the end of those 3 months I was still just as bad and couldn't come back to work so they fired me. My worse fears had come true; I lost the amazing opportunity because of my illness. I was completely heartbroken. I felt like the biggest failure. Not to mention all of the physical pain.
It was a huge, difficult decision, especially for me because of how much I loved my job and working in general, and because of the opportunities I was loosing...but the decision was the right one. I knew it then, and after a year out of the workforce being able to concentrate on me and my health it proved time and again that it was the right decision. I could have gone on disability as my doctor suggested, but I personally didn't want to. Fibro has already taken so many goals and possibilities from me, and I didn't want it to take away working. Yes, I'm stubborn. lol After that year off, I was able to go back to the workforce. I don't have as bad-ass of a job that I did before, but at least I get the satisfaction of working. It's with the same company (different business within the company though) so I still have the flexibility of working from home when I need to. If it wasn't for that, I wouldn't be able to be employed at all. So again, I'm lucky in that regard.
To answer your question about what was the last straw to leave the workforce, it was the point when I no longer contributed ANYTHING. My doctor's knew my situation well (how many years I've been in pain, and that it must be bad if I'm saying I can no longer function at all), so my primary care physician and neurologist were both happy to write a note for medical leave. As for disability, like I said I never tried, but every single person I've talked to that is said it was difficult. You'll likely get turned down the first or maybe even the second time, but try again! Do you have any other conditions besides Fibro? Most people have said that if they only had Fibro they would've had even more difficult time getting it, but because they have something else (chronic migraines, diabetes, etc etc etc etc) it was more likely to get accepted.
I hope this was a little helpful at least. I think you'll know what the right decision for you is.You have to take care of yourself. <3 Best wishes to you!