If you don't feel comfortable with the dentist, you should go to one that a friend or family member knows and trusts. It is too difficult to tell what has happened without examining you or seeing x-rays. Good luck.
What kind of symptoms are you getting with this tooth? Sensitive to hot? cold? hurts when biting? or nothing?
The feeling like tin foil makes sense since it was a silver filling. it takes a full 24 hours for a silver filling to set completely.
if the filling is not deep, you should not be needing root canal tx. the foil taste usually goes away in a few days. i would get another opinion at this point, preferably from a dentist you are referred to by a friend or family member.