I was diagnosed with a non-terminal chronic illness sometime back. It got worse, and the medication provided me with a constant headache. I only found out that headache was a side-effect after a subsequent Doctor's visit, who changed my medicine to some improvement. One reason I assumed it got worse was because I neglected medication in priority of other commitments, work and otherwise.
So I decided I need time off (after having suffered from the side-effect for about a month), informed my manager (who is great), and informed that I might take extended leave. They agreed. At the time, our leave policy allowed time off for people on Probation. But one day after I left, HR altered it. And now I require a medical certificate. I assumed it would be no issue since I've been visiting this doctor for months.
My doctor however while having acknowledged that the headache was indeed a side effect, said that I wasn't "unfit for work", and since the illness does not have an end-date, he can't recommend the requested time off. I requested a letter acknowledging the sickness.
My employer said a note would not be enough. While I can get a medical certificate from another practitioner who is more sympathetic, I'm having trouble with the ethics of the situation.
I don't want paid time off (which I will get if I present the certificate). And my health gets priority over any job, so I don't mind resignation. But I am grateful to my manager, and would like to make a proper exit in the recent future having given proper notice.
What's the right and ethical way to handle this?