The problem you would be having is a deep decay between two teeth ,so u can't see the cavity...or it could be pain due to impacted wisdom tooth.
For immediate pain relief take Tab. Hifenac P 2times per day.
Lukewarm water with salt rinses also you could do.
Next Steps
Visit a dentist nearby, they will take an x-ray and tell you what the problem is and treat accordingly.
Health Tips
Visit a dentist asap