I have severe dental pain at bridge. the pain goes away withcold water but returns after i swallow. what should i do?

Dying Nerve: Generally if hot things bother a tooth and cold relieves the pain, it means there is inflamation of the pupal tissue (the nerve in the tooth). This is a result of the nerve in the tooth dying. As the nerve dies, it forms a gas trapped inside the tooth. Warm temperature makes the gas expand causing pressure in the tooth resulting in pain. Cold makes the gas contract and relieves the pressure.

How about hot?: Dental pain under a bridge that gets better with cold is usually related to a tooth nerve that is dying. You should see a dentist asap to have it checked before it abscesses causing potentially serious problems.

Root canal: Seems like you need a root canal in one of the teeth under the bridge, go back to your dentist for a x-ray and tests to determine the cause and treatment needed.

See a dentist ASAP: The damage to the nerve is irreversible and the tooth if restorable needs to have a root canal therapy. Good luck.