Question! Baby sleeping!

I have a two and a half month old daughter who was doing GREAT at sleeping. I never really had to train her to sleep better at night because it seemed to automatically happen. Naps during the day would last about two hours and at night she sticks to a bedtime routine for the most part. But, for the last couple of days she isn't sleeping as well as normal and I'm not really sure where it's gone wrong at. She's wide awake at 3-4 am after her bottle. She doesn't really have any long stretches of sleep during the day so I'm not really sure why she's deciding to stay away this early in the morning. Her longest stretch of sleep is usually from 8:30/9pm-1:30/2.