I have just realized... I stopped eating chocolate in any form about three months ago.
This must not continue. I need my theobromine.

Fortunately, there's some whey protein powder that I got to make smoothies for Penny some time back.
However, the whey powder has an unpleasantly weak taste.
Fortunately again, I have cocoa powder and sugarfree chocolate flavoring.

Let us see whether this makes a difference in my sour mood.