The dirty, dirty yellow teeth needs to checked clinically by a dentist and it will be treated accordingly.
Next Steps
For temporary relief before you visit the dentist, please take a mild painkiller like Dolo 650 after food and gargle with warm water and salt solution 5-6 times a day. (If you are allergic to Paracetamol do not take the above drug and I have not mentioned a stronger painkiller as it needs to be prescribed only after thorough examination).
Health Tips
Please visit a dentist as soon as possible.