Minecraft Launcher completely locking me out of my account

I was chosen to judge a Minecraft online build contest, and when trying to access Minecraft today, it consistently flickered on-and-off between "Play" in the Minecraft: Java Edition menu and "Play Offline" every one second or so. I logged out of my account, and back in, but now it claims that I have never bought Minecraft (I have) and that I need to re-purchase it. (It also claims I have not purchased Minecraft Dungeons, which I purchased the Ultimate Edition of.) I do not have screenshots, but earlier it told me that I needed a username to play (Which I also already had, 'indycallisto'.). My review of the builds in the contest is due tomorrow, and I don't want to let the moderator team down. I also don't want to lose EVERYTHING I'VE EVER MADE. A few days ago, I switched the email on my Microsoft account, which seems to have started the issue, but I don't even see how that could have caused this. The one part I find strange is that it kept the names I created for each of my installed versions. I don't want to lose everything; please help!