I had some huge amounts of time off work for IVF. The medical certificates usually just said "unfit for work" or if they were trying to be a bit more informative they said something along the lines of "undergoing extensive medical testing and hospitalisation". I had OHSS twice and spent a week in hospital with it at one stage and over a month off work due to that cycle and nobody ever quibbled about the medical certificates I handed over.

Also in the midst of resigning from said place of employment due to ongoing medical issues and I've had about three weeks off work now and the medical certificates simply say that I'm unfit for work from XX date to YY date and no reason given. I believe they don't have to give a reason at all, and just declare you as unfit.

Are you a member of a union that may be able to help you out?

BW