Morning sickness is a reassuring sign. It isn't because of the vitamins you are sick, it is the pregnancy that makes you feel ill. The vitamins only intensify it or bring about those icky feelings.
Symptoms come and go throughout pregnancy. Some days you'll feel extra crampy, some times you won't. Eventually that crampy feeling goes away anyway (at least it did for me and most women I know).
Just relax. Baby is probably dozing soundly and in baby bliss in utero.
Your probably being paranoid - as I am too. I am 4wwks, 5days and was freaking out b/c my boobs arent sore, I feel great, and there's not a symptom in sight. I thought maybe there was something wrong and so I took "a few" pregnancy tests all to find out my line is getting darker. Don't think about it ( I know easier said than done). Seriously, I decided I will take all precautions, take my prenatal, eat right and whatever happens happens. Then when 12 weeks hits, I will have a little party in my head :) I hope that helps.