So my employer called today demanding to know the nature of my illness. I told them it was confidential and they said that wasn't good enough and hung up on me.
There will be hell to pay when I get back.
Unfortunately unsurprising to hear that.
If it's ongoing medical appointments then it's probably courteous to produce certificates for them (without the details). And sure it's nice if they are concerned about you and ask what's up, just say you're not 100% but thanks for caring.
But this is clearly not how they feel about it, sounds like they don't give a stuff about your health, don't trust you and just want you working.
I resigned partly because of it and couldn't work for an a-hole any longer. I had nothing else lined up, but it was such a relief to get out of there. Even if unions could help I'd still be working for that a-hole. I knew for years that I had to leave that environment, but doing it was the thing. I don't regret it for a second.
You know inside what's good for you and what's not. Give yourself as much time as you need. I'm not an expert, just what I did.