Hello,
As your child is 3 years old pain can likely be due to caries. If possible avoid
sugar in her diet. Also avoid chocolates, stick foodstuff, chips and bakery products that can worsen the problem.
Caries can be treated with pulpectomy followed by crown.
Next Steps
If possible attached clinical pictures of her teeth for apt treatment plan.
Xray is required to assess the teeth and it's condition.
Health Tips
Consult a Pediatric Dentist for treatment.
Also brush her teeth twice daily.
Medication should be given only after consulting with dentist.