I've felt like this A LOT before, but as annoying as this sounds, things do eventually get better. I always remind myself that bipolar is cyclic in nature: mood swings cannot and do not last forever because they cycle. However, I think you've spent more time feeling good and stable than you have spent felt poorly. You can and will get better, and it's important to remember that.

In the mean time, how about going outside for a walk? I know you like walking and stuff like that. Do you like coloring or meditating at all? What about watching a funny movie or TV show? Journaling?

But as Daonnachd said, you should contact a mental health or medical professional if you feel you cannot cope. No one wants to see you get hurt.