11 week old eating less

Is anybody else’s 11 week old formula baby eating less? He used to down 4 ounces easily and even have a 6 ounce bottle before bedtime and sleep 5 hour stretches. The last 2 or 3 days I’ve been lucky to get him to eat 2.5-3 ounces at a time and now he’s back waking up 3-4 times a night.😩 I try to calm him down before offering a bottle, but he won’t take a paci or settle down until we give him a bottle and then he’ll only eat 1-2 ounces before going back to sleep. I’m a first time mom so I don’t know if this is normal or not. 😩