cold sensitive, then click sound, then no pain

[Drew]

I have a molar that has had previous work completed and developed a cold sensitivity shortly there after. the unsual thing is that i can hold the cold liquid on the tooth for appx 3 seconds and i feel a click sound/feeling and like that the switch is turned off and there is no pain assosiated w/ the cold sensitivity. this was a very deep cavity filling using metal alloy not acrylic and was a correction to previous filling that had went bad underneath. any thoughts? Drew.