I try to give him 5 Oz but he doesn't seem to want it but now all he wants to do is eat every 3 hours 4 oz and not sure if that's okay or not for him to change all of a sudden he's only a little over a month

sounds like he may not be getting full enough, my 4 month old drinks 8 Oz every 4 hours, & he was the same way before he kept eating and I figured out he wasn't getting full enough