Spitting up vs throwing up?

amarie • E.🐘 | 21.✨ | ♏️

We recently switched to regular similac & she did great! No spit up no nothing. Yesterday & today every time she eats she’s spitting up a few times every hour until her next feed? Why all of a sudden is this happening?? Is it the formula or nursery water? Is she sick? Help I’m a ftm & I’m seriously changing her clothes every hour