I am like this as well. I have never been manic, but I am treated for depression. Usually, there is no reason for my mood swings...I just get out of bed feeling a certain way, but I know if I give it an hour or two, it will change! I just go with it and try not to be too hard on myself for my perceived flaws. I find self-compassion goes a long way in helping my moods be more stable because I am not fighting myself.