Why is my tooth so sensitive to cold 4 months after having my bridge replaced?

I had a bridge for 15 years with no problems besides the porcelain was breaking down and the metal was starting to show through. The dentist replaced the bridge, but the color was off terribly so she had to then redo that bridge. So basically two bridge replacements in 3 months. Four months later and my tooth is so sensitive to cold, especially cold air. I never had any problems until she replaced my bridge. I know she shaved my original tooth down even more than it was.