Baby with no appetite

My 3 month old (just turned last week) has had no appetite today. Normally goes to daycare and I send 15 Oz of milk and he usually comes home with 2-4 so I think he's eating there. He literally has not cries for food at all. He breastfed at 7am for 15 minutes. Has taken 5 Oz since and it is 3pm now. Hes had 5oz in the time he'd usually have 11-13 Oz. Feeling worried.