To rescue a sick baby monkey, first ensure a safe and calm environment. Gently place the monkey in a warm, quiet area. Contact a wildlife rehabilitator or veterinarian immediately for professional advice. Keep the monkey hydrated using an electrolyte solution if possible. Avoid feeding it until you receive guidance from a professional. Monitor the monkey’s symptoms, such as lethargy, vomiting, or diarrhea, and relay this information to the expert. Ensure minimal handling to reduce stress. Follow all instructions given by the veterinarian or rehabilitator closely for the best chance of recovery.