Hmmm? My gums healed after amalgam removal. They had become very resected. Do you still have mercury in your gums? Do you have an amalgam tatoo on your gums? My gums do get worse when I get a candida flare up and I might get canker sores too then. I don't think that your mouthwash or toothpaste is causing it but I'm sure it is not helping either. Here is the product review for Listerine on the Environmental Working Group:

http://www.cosmeticsdatabase.com/product.php?prod_id=22688

When you are trying to chelate a neurotoxic poison you don't want to expose yourself to another neurotoxic poison. There are a lot of alternatives. I was using a mouthwash from my biological dentist that worked well - I think it was from the Dental Herb Company. When you floss you should just do it enough to get any food particles out - you don't want to tear into your gums. The coconut oil is antifungal so why don't you try swishing with it after flossing? I also got some aloe vera gel when my gums were bad and when I had canker sores and just left it in my mouth for a few minutes.