my son is almost a month old and just as of yesterday he has been throwing up his feedings and it's alot! it's coming out his nose. then last night he held down 2 ounces and had a really green diarrhea diaper. his first feeding this morning was also 2 ounces and he held that down but then the next one he puked up. he's having wet diapers but hasn't pooped again since 4am. he usually eats 4 ounces every 3-4 hours. I don't understand what's wrong