(((((((((Berries)))))))))))
I'm sorry you're so low again.

It's a horrible feeling being low, but it's even worse when you're coming down from a stretch of good days. I know how that feels first hand. Maybe making every day a party is a bit of a stretch for you. Maybe you could start small, by doing one kind thing for yourself every day instead. You could do something that doesn't involve a lot of energy or concentration, like lounging in the bath or watching a funny movie. When I'm feeling low, even half an hour of escape can make a world of difference.
You'll feel better again. These things come in waves. My counsellor suggests that when I'm feeling well, to write down what it is that's lifting my mood. A particular food, going for a walk, a book or television show I like, maybe a playlist of songs. She says that when we're low, we tend to forget that there are things we can do to help ourselves, and we become unable to even think of what those things are. I keep a list at the back of one of my notebooks and when I'm not feeling good, I try to force myself to do one or two of those things, and it usually helps. Maybe it's something you could put together when your mood is a little better, both as proof that you CAN feel better and suggestions for how to get that way. Sending lots of hugs and hoping this passes soon.