suggestions?

So my baby boy is almost 3 months old and up until 2 weeks ago, he's been an awesome sleeper through the night. Slept for 5-7 hours straight and when he would wake up, he would wake up to eat and fall back to sleep. Now he's wake up every 2-4 hours during the night. I don't know what happened. Anyone have any suggestions to get him back to sleeping longer periods? Thanks!