Due to the deposits , ur gums gave receded and there is an exposed part of the root portion of the tooth which has sensitive nerve endings and hence the sensitivity. I would advise you to use the Anti sensitivity tooth paste for around 10-15 days if the sensitivity is reducing please continue using the same.
Next Steps
if you feel gap is more between the gums and the tooth please visit a nearby dentist and you can get it filled with a cement which would definitely help you.
Health Tips
Avoid Using too hot and cold Liquids. Avoid delays in getting the treatment if sensitivity persists after initial steps.