when i had to face the fact that i couldn't physically do my work anymore, and that i wasn't really safe and didn't trust myself to care for the tiny babies i went to my neuro and told him i had to quit.

he agreed and make the necessary documentation in my chart. he sent me for functional capacity studies which i failed miserably but that also provided measurable documentation that i would need to get approved.

i got turned down the first time, got a lawyer and then got approved. but had to pay for cobra for 18 mos til all that happened. with the ACA who knows now about getting insurance.

get copies of your own records, tests, mri's etc. keep a medical file on yourself. if you apply sent the records yourself with return receipt requested.
i was told to treat my application as a master's thesis. be very detailed and careful. think carefully. when answering the Q's think about your worst day, not your best.

that's what helped me.