Sick off vitamins?!

I have been taking prenatal vitamins for about 8 months or so, and all of the sudden I started getting nausea, especially after I ate. I couldn't figure out why, I quit taking the vitamins because I pretty much was having a hard time eating and I know to take them with food. Aftet I quit taking them, about a week later, I felt/feel better. Anyone else with this issue??