Got filling on back bottom tooth 4 months back.they had to cut down into gum. after finished, it felt horrible sensitivity to hot and cold. they said it was a hard filling to do. so they finally redid the filling and this time its worse. what to do?

You may end up with a root canal then a crown for protecting that tooth. Good luck.

Where you informed that because of the difficulty of the filling you may need a root canal. The symptoms of sensitivity to hot and cold are clear signs the tooth needs a root canal. The dentist tried to save the tooth and now a root canal is recommended. Go back for a root canal or be referred to a endodontist, if you want to save the tooth.