No appetite, am I healthy enough???

I have been really struggling the last four days.  Throwing up all day till about 5pm, and can't keep anything down.  My cousin is a nurse and told me to try sips of coke, the sugar in it can help settle your stomach she says.  So I can keep that down and I'm trying to eat... Pretty much a few saltines and a yoplait yogurt once a day.... Is this healthy enough for he baby?  Pop and yogurt??  I usually eat really healthy, never drink pop and love my veggies and fruit but I cannot stomach anything else :/
   Also I have had a massive headache that I keep taking Tylenol for, and I'm worried that will hurt the baby too since I'm not eating!  :/