mood swings?

Just yesterday I was so motivated I woke up early for lots of things done around the house, worked out and cleaned the yard. I planned to try and have the same motivation today but I woke up late and I'm just feeling blah. Is it normal to feel like that? I feel great one day and the next I feel so blah and unmotivated... when I was in high school I was on medicine to help with my bipolar disorder and depression, so could this be it coming back now that I'm pregnant?? Thanks:)