Kindly visit near by dentist sir and by your post I feel you have an aggressive brushing habit do consult a dentist who can visualize the tooth and gum as well and suggest best for you  and brushing technique too Kindly check the bristle of brush preferably use soft one which will be written on top of the brush do check n buy

Please visit your dentist. After a clinic examination he will advice you the necessary treatment as to whether  you need a filling or a root canal.