Acetaminophen intoxication

A mother with cold is at home with her 3.5 year-old son. She has a fever and headache so she decides to use Panadol 500 mg and goes to bed. After 2 hours she comes back. Her son is laying on the floor, has a stomachache, is sweaty and feels bad. There are 8 tablets of Panadol 500 mg missing. What should the mother do?
3
years
14
kg