You might need an antidepressant or something to go along with those two drugs. Lithium treats both mania and depression in bipolar disorder, so I don't know if adding an antidepressant will even be an option for you. I experience "flat" moods but it's usually just the apathetic/indifferent side of my depression. You will cycle out of this. I don't suggest you stop taking your meds. I do recommend getting a hold of an on-call shrink as soon as possible to discuss your options.