Naptime

For all of you that have kids already, I had my son september 28th. So he will be a month old tomorrow, well he used to be really fussy ALL the time. So we changed his formula to gentlease and it was great for about a week or so. Now we are back to screaming cry and fussing all day long. I dont think he is colicky or needs soy because he sleeps absoueltly wonderful at night. He absooutly refuses to take naps during the day so I am wondering if he gets overly tired? Ive tried everything he just will not go to sleeo during the day. What can I do?!