I had COVID at the end of 2022 and became deeply and severely depressed right after and for the first several months of 2023. It was terrible. I was shaking uncontrollably for days, I never slept for more than a few minutes at a time, I didn't eat, and I had panic attacks constantly. I really thought that it would never end and that my brain had somehow broken.
I did have stressful events I was dealing with in life before this occurred, but I was managing. While I had COVID, I realized that I would get very unexpectedly sad and sometimes cry for no reason. As COVID got better, my depression symptoms stayed and got worse.
I ended up sick with something that required antibiotics and within a week of taking those, my symptoms started to ease up. A month later I was doing much better. A few months later and I was back to normal. I also started therapy during this depression event and continue it today just in case.
I really don't have a way to prove that it was connected to COVID or the antibiotic use, but I can tell you that my mind was not functioning correctly during this. I could mentally know everything was totally fine, but my body would still decide to dump adrenaline and fear on me unreasonably. It was like being trapped in a broken body that was torturing me. People would try to tell me that everything was fine, and I would explain that I knew that, but my brain chemistry was still on fire and logic didn't help.
Anyway, I fought hard, I reached out to friends, I did therapy as often as I could, I started exercising, did breathing exercises, took lots of walks outside, and I eventually got through it. It felt hopeless but I just did those things anyway through sheer force of will. Eventually I got through it and that hell is only a memory now that continues to fade with time.
I believe this was related to some kind of inflammation somewhere that was linked to a very bad COVID infection.