NEED HELP!!

I know this is a group for TTC, but I feel like you guys will understand more than most people! So AF showed yesterday and now I’m just in an extremely bad place mentally. And I’ve been overworking myself, so I want to call out of work. I just need one day to myself to get myself together mentally. I have no idea what to tell my boss, though. I don’t want to use the cliché “sick” excuse. Should I just be honest and say that I’m not doing well mentally today? (my boss already knows that I have been diagnosed with depression, and normally he’s understanding). I just mentally cannot do it, guys. I really thought this month was my month..