Baby not napping

So my son is 4 months, and he just simply doesn't nap. He used to nap pretty good, but for the last couple of weeks he hasn't taken a nap really at all. Some days he'll fall asleep for like 5-10 minutes but that's about it. He's also not really sleeping at night anymore. I'm just not sure what's going on. It's not a huge deal to me but I'm worried he's not getting enough sleep. He's also been fussy and pulling off the boob and crying when I feed him. Any ideas what's going on?