Site displaying Internal Server Error 500 just as suspicious comments flagged as spam

In my 13 years of Wordpress, I've never seen anything like this. About an hour ago I was alerted by one of my users that the website was displaying an Internal Server Error 500 message on every page. I consulted my host's tech support, and they were unable to determine the cause. I then noticed that I had about 20 comments in the moderation queue, all of which are very suspicious (see screenshot). I have no idea what to do. The website will load intermittently but it is very slow. I'm not sure what's going on, and I have no idea what to do. Any help would be greatly appreciated.