Take an x-ray and rule out the cause of the pain .in case there is deep cavity present and there is periapical infection then rct should be done .and if the tooth is grossly decayed without any chances to save it then extraction is advisable.
Next Steps
visit a nearby dentist ...and to get relieved from the pain take proper medication prescribed by the dentist
Health Tips
warm salt water gargles will also be of some use to reduce the pain.