You should definitely see your dentist
. Tooth sensitivity occurs when nerve roots are exposed from under the hard protective covering of the tooth. This is common with cavities, as the bacteria release digestive enzymes that destroy the tooth substance and expose the nerve roots, leading to cold or warm or sweet sensitivities.
This should go away when the cavity is filled, and if it has not this might suggest that there is ongoing infection under the filling
or that the filling is loose and allowing air and other substances to enter. In other words, your dentist may need to re-do the filling.
If you are experiencing more generalized tooth sensitivity (not just limited to the one involved tooth), then their are some other possibilities. These could include a general erosion of the tooth protective covering because of acidic foods, acid reflux
, or excessive use if whitening product or whitening toothpastes. Gum disease or gingivitis can also lead to generalized tooth sensitivity by causing exposure of the sensitive bases of the teeth.
Either way, the first step is to explain what is going on to your dentist and see what possible causes and treatment options they might recommend to you.