Hello you need to visit the dentist and get it checked. Get a deep scaling and polishing done. If there is a cavity get it filled. For sensitive teeth you can use any good sensitive toothpaste available in the market.

Hello sir. You need to visit a dentist and get a clinical examination and x-rays done. If the xrays suggest a infection it needs to be with rct and medicines. Avoid hot and spicy food for the next few days. It will only aggrevate the pain. Try warm saline gargles 2-3 times to reduce the pain temporarily.

Hello Sir. Greetings of the day. You have to visit a dentist and get a x-ray done with the tooth which has pain. The pain might be due a deep cavity present or due to bone loss between two adjacent teeth. If the extent of the cavity is deep you will have a get a root canal treatment done followed by a cap and if the reason is bone loss, you need to get a deep scaling done to remove all the deposits which are not removed on regular brushing.

What I can understand from your question is that, you have PYORRHEA. There must be bone loss between your teeth and roots might be exposed. This occurs due to external deposits on you teeth (Stains and Calculus). Probably you need Oral Prophylaxis (Cleaning) of your teeth from a dentist, and a toothpaste for sensitivity for longer duration and some oral gels and medications. As the kind of pain you are telling, there might be some caries (cavity) in your tooth/teeth, which can be diagnosed by IOPAR (X-Ray) only.