It's normally called a sleep regression. Definitely read about it to prepare yourself. My son went through them every few months.

I have the same problem. I hear it's normal. Sometimes my lil one still sleeps through the night. But other night's shes up at 2 or 3 am. It could be there teething. Another thing that helped me was I sometimes put bby cereal mixed in with her formula only before bed. And she's out all night