L.A.
Yes, the allergies could be causing that morning vomiting.
Get ready TMI..
I had morning sickness all the way through my pregnancy, even the morning I was in labor. I would get up, brush my teeth, vomit, brush my teeth and go on with my day.. It looked like bile and drainage, so hard to know the difference each morning..
I still get allergies with drainage in the morning and many times, end up vomiting..
You may just need to consider continuing the zophran and see if the drainage is still making you so nauseous..