My tooth was sensitive to cold and hot i used sensodyne and it helped now i have no sensitivity but now i have constant pain. dentistnohelp/jumpthegun?

Can be difficult: It can be perplexing trying to determine the health of the pulp(nerve) of a tooth. There are some pulp vitality tester but not always accurate. Judging the signs and symptoms of a tooth may all you have to work with. I am sure that your dentist has tried to rationalize what could cause such an event: large or deep filling, trama, cracked tooth, etc. You may want to go to a endodontist.

Probably infected.: If you have a tooth that gives you constant pain, it is very likely infected. See a dentist asap. He will probably prescribe antibiotics until treatment can be done, which needs to be soon.

Bigger problem: Sensodyne does not work for all dental pain. It does work to reduce cold sensitivity, but heat sensitivity is a whole different story. If you have a deep cavity or a damaged nerve sensodyne will not reduce the pain. Now having constant pain i would imagine you have a cavity into the nerve. Go get it checked out.