Thank you for your query,
This high grade fever and vomiting
and inability to walk looking like Viral illness with myositis
or mayalgia.Continue Tylenol for fever every 6 th hourly, do tepid sponging with lukewarm water whenever there is high grade fever.
You can give sips of oral rehydrating solutions to prevent dehydration
Consult your Pediatrician
or Emergency as early as possible as there is high grade fever and the inability to walk is an alarming symptom to see your Doctor.
Hope i have answered your query.