I suddenly ve extreme sensitivity of all teeth, and drinking water [which is not very cold] hurts badly on all teeth, what may b the cause, ? pls help

Nerve exposure: The sensitivitity is probably due to a nerve exposure. Since is appears over the entire mouth it is probably not decay, but root surface exposure. You can try otc desensitizing solutions like sensodyne tooth paste, or a mouth rinse, or see your dentist. Another way is use a tray like the periotray to hold the desensitizing solutions in place long enough for them to work. See your dentist.

See your dentist: You may have root sensitivity from brushing too hard with a hard toothbrush. If so, brushing gently with sensodyne toothpaste may help. Best to see a dentist for a proper diagnosis.

Check your paste: Sometimes you can react to ingredients in your toothpaste. One culprit can be pyrophosphate that is the ingredient that is added to tartar control tp. Sometimes whitening agents do it too.