My sisters baby just blew milk out her nose and stopped breathing for thirty or more seconds turned dark blue then started to cry is that normal??????

No: Depending on how old your sister is infants are obligate nose breathers. If she aspirated milk into her nose she couldn't breathe until she cried and used her mouth to breathe. She will acquire the ability soon to breathe with her mouth, but until then be careful and make sure her nose stay clear and open. If she continues to aspirate milk into her nose see her pediatrician.