What Causes Constant Vomiting In A Toddler?

Hello doctor, my son - 19 months old - vomited four times within a span of an hour last night. First, it was his lunch that he threw up. Later, it was more of mucus and every water intake he had. My doctor prescribed Emset 3.5 ml to stop his vomiting. Once I administered lesser amount (1.5 ml) of medicine, he vomited that out too. However, he slept without eating or drinking after that and woke up in the middle of night while showing signs of being hungry. I breast fed him and gave him bottle feed as he was far from being comfortable and sleepy. His feet and palms are exuding heat. Though there is no incident of repeated vomiting, but should I continue with Emeset? And what should be the right dosage?