Have you been on a drip for rehydration at any point since this thread started? If you haven't you need to be either presenting to an ER or getting an opinion from your Dr as to when you should go. Hydration is key in your position, the key danger and key to feeling better.
Also with the Zofran I find it works best if I take it before getting out of bed and I stay laying down for 1/2 hour after I've taken. Also, in consultation with my OB I am splitting my dose (breaking the wafer in half) and having half in the morning and half in the afternoon which seems to be working better. Maybe check with your Dr if this is an option for you?