I am not a fan of extracting teeth. If it is not a wisdom tooth(rearmost molar) then you would probably need an implant or bridge to prevent the nearby teeth from shiting too much and in order to chew properly. An implant seems like a major ordeal and quite expensive.

I guess you should probably have the filling replaced by a regular dentist.

It is very doubtful that you have mercury poisoning from just one filling. I had 25 mercury fillings replaced. You might have lead poisoning or perhaps mercury poisoning from fish or other sources. Your problems might be caused by parasites. Have you done some parasite cleanses? There are cleanses with wormwood, black walnut green hull extract, and cloves that are effective against most parasites and help fight candida. Eating raw garlic(perhaps one clove(section) right after each meal can also help
fight parasites and candida.

Do you take in enough iodine? Are you overweight? That might point to a thyroid problem or iodine deficiency. Do you often get athlete's foot, yeast infections or jock itch? If so, then you may have a candida problem. Do you eat many sugary foods or drink alcoholic beverages? These encourage candida growth and should be avoided.