It's a medical reason. Medical reasons are always fair excuses. I'm really sorry about how your superior treated you that sounds really shitty.
Idk if it's the same but last year I had to withdraw from 4/5 classes in the spring semester bc I'd been in the hospital and there was no way to make up the labs in time. But then before my only final I just randomly decided to take like 5x the amount of one of my nonlethal medications. But I got to class and I was like...I can't tell my professor sorry, I decided to not really od so I can't take the final, like she'll think I'm making it up or scared of the test. But when I was taking the test I was totally spacing out and my vision was blurred and I was falling asleep and I knew that it was terrible. I think given the way that year had gone and the fact I had been a good student all year, I might have had a valid excuse to retake the final. But I just turned it in and left. I didn't want to explain, or to be told I was faking or gaming the system. So even though I knew I probably had a valid medical excuse, I didn't feel like other people would treat it like it was valid.
I know it's just a final, not like a job and no one attacked me. But while I think mh issues are real excuses, I think the fact that so many people brush them off makes it scary to try to use one