Zofran having the opposite affect?

I was prescribed Zofran by my OB. I've noticed that either after I take it, I feel worse, or I start to feel better when I don't take the 2nd dose on time. Yesterday, I decided to do an experiment on myself... I didn't take the Zofran at all yesterday & I felt better than I have in months. I only got nauseous twice for a short period of time. Today is my 2nd day without Zofran. Aside from still having excessive saliva, I feel great.

It helped tremendously at first, but now seems as if it exacerbates my symptoms.

Has anyone else had this experience?