Gold Filling - leave it for now

Don't worry about the gold filling, take care of the amalgams.

Whoever put the gold filling in - your current dentist or a previous one - you have the right to ask them what is the composition of that filling, and they are obligated to tell you.* It may have a little nickel in it, which may or may not be a problem. Focus on the amalgams. Once all the silver/mercury is out, there will be much less of a galvanic effect (and out-gassing of metal from the gold filling) because you will be down to, predominantly, one metal.

*If you're not good at making phone calls like that, tell them you have mixed metals in your mouth and some weird symptoms you're trying to get to the bottom of.