My dog has a "skin tag..

He has always had a black mole -like growth on the outer part of his chest...everyone assumes it is a nipple or skin tag. For 6 years it has looked the same, then 2 days ago it started swelling, and filling up with fluid. It is now the same color he is , brown, but as it continues to grow I can see the skin stretching so it will probably get lighter in color. Right now it is resembling a large acorn in every way, just no acorn hat, :) or a large brown grape. He is fixated on it now and licks it all the time. It looks gross, looks like it could be painful, and honestly I am afraid he might try to chew it off. How serious could this acorn be and is it a nipple, mole, what? He is a boxer rott mix, and I have noticed a few other spots that are small but black and fleshy kind of like this one used to be. Any advice would be great. Vet says 400 dollars to remove it, but I am a couple zeros shy so is there a home remedy? thanx much!

take him to the vet and have them look at hit because it could be a type of cancer or disease and you may want to take care of it before it gets worse

id take him to a diffrent vet because my vet removed something like that off my dog and charge around 80