U need to apply anti sensitivity toothpaste like sensodyne for temporary relief and firther i need to know more consult me

You need to get an x Ray done along with a clinical examination from your dentist.Depending on the amount of tooth structure a decision can be taken if it is very close to the pulp(nerve) den you will have to do a root canal treatment.

1.It might be because of abrasion or Abfraction Abrasion is more common of the two, the wearing away of the enamel and dentine near the gum line due to vigorous tooth brushing or wrong brushing technique. Which will lead to sensitivity due to exposed dentin It can be treated by filling that area with GIC or composite (tooth coloured filling ) . Start Using sensitivity tooth paste . Abfraction is due to constant biting or clenching of your teeth which will cause tissue loss in that region. 2-Another possibility is it might be class v cavity .if the cavity touches the nerve of the tooth you might have to undergo root canal , if it’s just a small Cavity filling will help Diagnosis is very important to differentiate b/w all these possibilities & for proper treatment ,so please visit a dentist near by for further help. Thank you