I had a left lower inner tooth pain for a month before 2 weeks.now i have gum swelling under the same tooth and with no pain on tooth and gum .?

Infection: Your description of progressive symptoms sounds like an infection is present in this area it could be in the tooth or the related structures. I strongly advise you to have the area examined immediately to avoid the possible spread of the infection. Your dentist will be able to identfy the source and recommend the required treatment.

Chronic abscess: The tooth evidently had a nerve problem which was the reason for the pain. Very often the nerve or pulp wil die completely and the pain goes away. The swelling is a sign now of a chronic abscess or infection. The tooth will probably need either root canal therapy or extraction.

Possible: It is possible that your pain was from the nerve of the tooth dying and now you have an abscess forming at the root end. Its best to see a dentist to have it checked before you end up with a serious abscess that can spread into your blood stream.

Abcess : Seems like the nerve in your tooth is dead and infected, you need to see a dentist to get the right diagnosis and treatment , possibly a root canal.

Pulp disease: You describe the normal progression of dental pulp disease. You roughed it out through the inflamed and painful pulpitis stage and now the pulp has died and become infected. An abscess has now formed and you have swelling. See an endodontist. You need root canal therapy asap.