What anonymousforever said re. the get on the cancellation list. Do a call around to see if you can see an alternate specialist too. Make sure you mention again that it is for a FMLA claim and your time limit.

Don't resign under any condition is the number one thing as even if the FMLA thing does fall through you can still make an ADA discrimination charge with the Equal Employment Opportunity Commission and/or FMLA discrimination claim as FMLA can still be approved retroactively even if no longer employed there.

First up - I assume that the information you have received from HR has been in writing? It is outlined very clearly by the Dept of Labor that anything regarding this process, their expectations and your future job prospects needs to be in writing.

I am from Aus and although I do work in Industrial Relations I am just trying to help out a fellow migraneur. Your next phone call after the specialist should absolutely be the dept of labor to confirm/clarify this info and make sure you are on their database as calling/making an effort.

From what I can see in the FMLA Act 1993 you must obtain that certification as you mentioned but it says in 15 days, (that is still harsh). However, it says that is - unless circumstances make it impracticable to do so despite the employee’s diligent, good faith efforts. (i.e. doctor being unavailable).

This is why the email you wrote to your boss was a brilliant idea. Under FMLA laws you have to show that you have made diligent, good faith efforts to return the certification on time and you are doing just that.

Your employer will not be able to just fire you on day 15. What happens on day 15 is that your employer must send you something in writing to say you have not submitted sufficient evidence. You then have 7 days from the receipt of that letter to then submit your certification. Even then it says - unless the time frame of 7 days is insufficient. Just as long as you are making a diligent, good faith effort to obtain that certification/evidence.

Do you not have any leave entitlements at all that you can access? I know us migraineurs usually don't have any leave left but if you can use some then do so. It would certainly relieve tensions between yourself and your employer. I doubt you'd be asking if you did have entitlements.

Please call them asap: http://www.dol.gov/whd/forstatelocalgovernments.htm

Other than that, good luck!