11 month old help

Can someone help me 😂 I'm losing my mind. A little backstory. My identical twin boys are 11 months old now, they have been sleeping through the night since 2 months. They take 3 8 oz bottles of formula a day. They have two naps a day and they go to bed at 6:30 P.M

Well, recently they haven't been finishing their bottles at all. They have been leaving 2 to 3 ounces in the bottle when they decide that they're done...AND they have been getting up and screaming every two hours at night. I don't know why. We make sure they eat before bed and that they are fresh and clean and that nothing is wrong with them. Then they scream. We check on them. Then they scream until they fall asleep. Then they wake up every two hours after that and repeat the same thing. Scream, check on them. Scream, fall asleep. I don't know what to do anymore.