Just took a pregnancy test and it's positive! Yay! Should I start prenatal vitamins and folic acid? Where to buy? how much? When should I go to the Dr? By my calculation I must be in week 4 right now.

hi I'm 5 months pregnant so the doc gave me those pills to help the baby grow,I drink them at night because if I drink them in the morning I vomitt them out...but even if I drink them at but I was wake up in the morning nd vomitt.....is it normal or I have a problem?