Dont neglect. Show to a good dentist as soon as possible. You may be having caries or something which requires urgent attention.
1 Doctor agrees with this answer
I have a similar problem but sensitivity in my teeth has been there for months.My gums had receded over a period of time due to forceful brushing. I am very careful to use the extra sensitive brush, no force while brushing. The sensitivity is still there. I met two dentists. One of them suggested that sensitivity will be there for some time and then it will get ok if I do not brush hard. The other one said that once enamel is eroded and I start feeling the cold sensation, it is not likely that it will go away so I have to just take precautions as it cannot be cured.
If this is the first time u r having sensitive tooth and suddenly started, and no other problem like bleeding etc, maybe its due to some very hot or cold thing u ate or drank. wait few days. it may go away. use special toothpaste for sensitive teeth and brush very very gently.