Please Don't consume betel nut as it effects the oral mucosa by increasing the rigidity & gives rubber like consistency to the oral mucosa & may give burning sensation to it.
For details regarding reduced mouth opening & to also evaluate the condition of the teeth whether 3rd molar is erupting within the mouth clinical examination should be done
Next Steps
visit dentist who will evaluate the condition & will perform the treatment accordingly
Health Tips
please perform mouth exercises as advised by the dentist & Gargle with lukewarm salt water after every meals to maintain oral hygiene