Formula for spit-up?

I recieve formula from WIC so I had to take my daughter to her pediatrician to change it. I told him all her symptoms and I assume it's a sensitivity to cow's milk (I have gotten rid of dairy because I'm breastfeeding as well and she feels better now). The only symptom she DOESN'T have is spit ups. So why would he precribe the spit up formula rather than the sensitivity formula??? I'm just confused here. Similac brand. I'd like to add that the only reason we use formula is because sometimes she doesn't get full after i feed her, usually at night. So she eats a max of 6 oz