C.R.
The prenatal vits were the culprit for me my second pregnancy. After my first trimester was over when my nausea wouldn't go away my friend told me the prenatals used to make her sick. Once I tried not taking them it went away almost immediately but when I took even half a day I would have nausea for 2 or 3 days afterward. I stopped taking them after that and just focussed on nutritional eating.
P.S. Craving sugar is a sign that you might need protein. I didn't know this my 1st pregnancy, ate fruits & sugar nonstop, and had to go for a 2nd round of glucose testing b/c my sugar was high. I knew about it the second pregnancy and ate more protein and craved way less sweets and my first glucose test was normal!