Mama cat suddenly aggresive to 3 year old son - Any ideas?

I don't know, cats are weird. My mom cat can be a real witch sometimes and will start fights with her kids. I have her boy and her girl babies and gave one away. Sometimes cat mos like real moms can just get cranky and tired of stuff. I'm sure as a mom yourself to a 3 year old you can sympathize with wanting to be left the hell alone once and a while LOL. If it gets any worse I really would say to just call up the vet. There's really not a reason to take them in unless they are sick. Any of them get into something that made them smell different? For now, just keep your son away from the cat. Give it some time it should settle.