Why is my puppy shaking its head rapidly and throwing up.?

i have a 4 week old orphaned labradane and ive had him for two days and i have been feeding him 2-3 times daily with lamb and rice soft puppy food soaked in premium milk replacer and he is shaking his head rapidly and throwing up for the past 30 minutes i just need to know what is wrong with him and what i should do thanks...