In goldfish, white edging to the tail and fins is just about always caused by water quality. The white bits coming off his head are probably excess mucous too.
It's unlikely to be a protozoan infection because you haven't introduced any new fish or plants in the last few weeks, (in your case 6 months). And the fish not rubbing on objects would also suggest no protozoan parasites.
You do have an ammonia reading and that will stress the fish and cause this type of issue.
Chemicals can sometimes get into well water and cause this type of problem.
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How much water do you normally change when you do the water changes?
Do you gravel clean the substrate each time you do a water change?
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Do you aerate the well water before using it?
Ground water (well or bore water) has normally had all the dissolved gases removed from it and it is a good idea to aerate the water for at least 30 minutes (preferably 24 hours) before using it in an aquarium. This allows the water to absorb oxygen, carbon dioxide & nitrogen gases that are required by the fish.
You should also test the well water for anything you can (ammonia, nitrite, pH, salinity, etc) before using it. Chemicals can leech into the ground water and cause problems to fish. A quick test for ground water is to fill a glass with water and sniff it. It should not have any smells. If you hold the glass up to the light it should be clear. These are 2 things you can do but it's still a good idea to check the ground water for ammonia and pH at least once a month or if the fish ever has any issues.
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I would stop using medications and do water changes.