Prenatal Vit. Causing Morning Sickness

During my first pregnancy 5 years ago, I has "morning sickness" all day everyday for 7 months! One day I forgot to take my prenatal and suddenly felt better! The vitamin was causing the issue! At that point the OB said it was safe to just switch to a regular multivitamin 1.5 doses per day. My baby girl was healthy and strong! 
Well, at 12 weeks now, I am suspicious that my nonstop sickness is caused by the vitamin again. I skipped it last night and took the multi instead. And I feel SO much better! Now I am not sure what to do!
Anyone else have a similar experience?