Welcome to PMS...for the next ## months. At least that's how I'm seeing it. I am week 3.5 and my patience is tissue paper thin. I think that it'll continue to get worse or maintain. I have let coworkers know that I'm on a different regimen that may affect my mood and apologize in advance. When it comes to customers I just have to put them on hold sometimes, take a few deep breaths and then continue.
Oh, and exercise helps mood
I walk about half an hour a day and my attitude is dramatically better until the end of work (I walk about 3 hours before the end of my shift).