@Supanova: You're right, it's not really a mixed episode. It seemed the closest comparison I could use. These are dangerous moments for me, though.

My question to all is: What do we call this? I don't believe there's anything in the DSM which addresses it. These are precipitous drops into depression and impossible to work myself out from, most strange because the stimulus is a positive experience. It's so sudden, I can't fight it.