Try taking them right before bed. Its normal, you just have to find the right ones for you. I have the same prob. and which to a chewable kind which work out great.
I can't swallow pills too well, especially the huge prenatal ones...so I take the flintstones chewable. I took them when I was pregnant with my son and it was fine. I wasn't able to take them in the 1st trimester because I was so sick, and the same thing this time as well. I had to take them in the 2nd trimester until the end, and it was no problem. I would try switching to another kind and see if you feel any better.
I heard the same thing - I bought Walgreen's Prenatal Vitamins and every night I take one as I am climbing into bed, literally. With a biiiig glass of water. That way if it does have the potential of upsetting your stomach, you in theory won't be as uncomfortable when your brain and body are at rest. Or at least you won't be aware of it!
Prenatal vitamins can do that. Your doctor can prescribe a different one or give you samples to try until you find one that you like. Most likely, though, it's just morning sickness. I always feel more sick at night than during the day, so I jokingly say I have night sickness.
It will pass!