Hi, My 29 Month Old Occasionally Throws Up A Cottage

Hi, my 29 month old occasionally throws up a cottage cheese consistency vomit which smells disgusting. Sometimes its when you offer him food, such as this morning. He had some milk about 2 hours ago then we gave him porridge, he threw up as the first spoon reached his lips. Seems okay in himself. Not sure its an allergy to milk (he's on cows milk and has been for sometime). Any ideas? Thank you in advance.