Why won't my 1 month old nap during the day?

I have a 1 month old who used to take good naps (1-2 hours) during the day and sleep 4+ hours at a time at night in between feedings. The last 2 days he has when I lay him down he will stay asleep for 10 min or so, then wake up crying. I try going in to settle him down, then lay him back in his crib drowsy and he just keeps waking up. Nothing has changed in our routine, but he just won't stay asleep. He is still sleeping good at night thankfully, but gets so cranky from being overtired during the day.