Girls are already out of energy. They start to spit up and cry as soon…

Girls are already out of energy. They start to spit up and cry as soon as they give their breast, or option two, if they don't spit up then they just suckle for 3-5 minutes and throw it up, starts burping. At night there is much less of this: only in a sleepy state and at night and during the day. It didn't happen before, started a week ago. What should girls do? Is something wrong with the milk? I want to switch to breastfeeding.