Hello,
Seems that your angel is having intestine infection through some sort of bacteria or virus, which is responsible for loss of appetite, 
vomiting and sleep disturbances due to abdomen 
colic most likely. I would recommend that he requires:
- Consulting with his pediatrician
- Prescription of anti emetic syrup as ondancetron
- Antibiotic as 
cefixime or else to control infection of intestine
- Take care to avoid putting of toys in mouth while playing
- Hygiene care of mouth, hands during, before and after bathroom use
- Liquids at regular intervals to avoid dehydration
- Yogurt support intestine flora for faster recovery
Hope I have answered your query. Let me know if I can assist you further.
Regards,
Dr. Bhagyesh V. Patel, General Surgeon