I am drinking prenatal vitamins and I got 8 pounds, around 15 days , is it possible, or I am getting crazy

That doesn't sound right. It's more likely you are retaining fluid. Go and see your caregiver at once.

Thank you

How far along are you?

I am not a pregnant, I just won't a baby

If you are not pregnant, then no, you definitely should not be putting on weight like that.

Prenatal vitamins are fairly expensive. Why not just stick to the folic acid and regular vitamins, or even consider if you really need any supplement beyond the folic acid? You can keep the prenatals for when you do get pregnant.