Started intermittent fasting; now I’m having problems

I started intermittent fasting, and I was able to easily go a whole day without eating, but every time I eat now, I feel so nauseous and sick. I stopped the “diet”. But I haven’t been able to get my normal eating schedule again. I eat, and feel nauseous for hours, until I want to eat again then I feel ravished. Even if I eat slow I want to throw up and I feel weak. What could be wrong with me. I feel terrible. I wish I never tried it.