Chronic illness, no sick leave balance

I have multiple chronic illnesses that have been flaring recently. I have no sick leave balance due to my whole leave bank having been used a few years ago before going on long term disability. Since I returned to work, I have not accrued a sick leave bank since my conditions mean that I use my sick leave basically as quickly as I accrue it. Since running out of sick leave, my manager has said that all future leaves must be "proven" with a doctor's note within 24 hrs, even if that means that it must be sought from a walk-in clinic. Leave without pay will not be approved. My condition is such that going out during a flare makes it significantly worse, so going out to get a doctor's note is not healthy or safe.

There are performance issues at play (due to my illnesses) and a functional abilities assessment has been requested but not yet completed.

Manager is aware of my limitations but has never managed an employee with chronic illness/disability and is, frankly, doing a terrible job. Increased micro managing is increasing my anxiety substantially and making all of my conditions worse, which is decreasing my performance, etc.

I am in the midst of a serious flare and have spent the weekend in bed. It is likely I will not be functional tomorrow morning. With the above statements about sick leave, I don't know what to do and am massively anxious.

Would appreciate any suggestions or advice from the hive mind.

Before anyone suggests it, I have meetings scheduled with disability office, respect bureau, union rep, but have not had any of them yet.