throwing up after feeding breastmilk

I do both formula and breatmilk to my 2 week old baby. Formula during day and breastmilk during night but for some reason tonight she threw up right after bottle breastmilk then after a while i gave her off my breast and right before she fell asleep she threw up again... can she be disliking the breastmilk?? and can i feed her again because she seems hungry?

Answer from the lactation consultant
It could be a number of things: she could be ill with a stomach virus, or she could be adjusting to the two totally different feeding sources. Formula digests really slow whereas breastmilk digests really fast. Alternating the two can leave some babies with digestive woes.
If in doubt, you can always nurse a baby again. The worst thing that could happen is for them to overfeed and spit up a little.

Liz Pevytoe, RN, IBCLC