exhausted and emotional

For some reason I've been very emotional lately and I can't seem to put my finger on it, I'm not stressed or anything. I'm also exhausted from working 5pm-12am  like 2 days ago. I mean yesterday I took a nap woke up and was still exhausted. I'm not really understanding what's going on, I had a one day period this month. And my next period is due May 4-6. I took a pregnancy test it was negative so I'm kinda confused not on anything that would make me emotional... 😥 I don't know what to do, what do you ladies think?