You can try using sensitivity toothpaste and soft brush . Still if it persists then there are 2 treatment plan
1. You can apply remineralisation paste or varnish or desensitiser.
2. Check for the cavity ( due to caries)or abrasion ( due to faulty brushing technique) or attrition ( due to tooth grinding- bruxism) and do the needful treatment
Next Steps
Please visit the nearby dentist , so that he could find out the actual cause.
Health Tips
Continue brushing, avoid hot and cold foods till you finish your treatment.
Hope this helps you sir