Yes, there can be bad days, but the sun will shine again..
I HATE those days with a HUGE, SERIOUS..um..BIG passion. It's hard to talk to someone, but I'm glad you are!!
I never got a chance to talk to someone those days, even though I should have. ICCCCCCCK. That's the best word to describe this. LOL.

But, lol, enough about me, um, yeah, I agree with using a journal! If you get these emotions on a regular basis, then maybe you should talk to a doc, but if it happens sometimes, well, it may pass..
It may be weird at first, but just write. And just be nice to yourself..it's helpful, but make sure you do it at least once a day..