I knew it wouldnt last

I knew the good mood would not last. I feel like crap at this very moment. Trying to make myself think about tomorrow and going xmas shopping, its something I am looking forward to so I’m trying to distract myself into thinking about that.
Sometimes my thoughts really scare me. I can go from happy to depressed in a matter of minutes. I can go from being on the up to wanting to be dead in moments. It sucks.