On lexapro (escitalopram) 15mg. it seems i keep having shifts from positive mood to negative mood continuously all day. like i can't seem to hold on to the happy.

Rapid shifts: This isn't easy. It's not old fashioned manic depression which has much longer moods. Neither last long enough to be real - more like a leaf blowing in the wind. A good therapist may help you learn to track your path and find clues to shifts. It will take serious effort from you to mature in mood tolerance. As a Mom, you may see how quickly kids swing - it may be similar. Lithium + stabilizers.