have you ruled out dropsy? it's a disease which the fish's belly appears bloated/swollen and the scales on the belly stick out and have a pine cone shape.
also, try getting some help from a goldfish forum like this one
http://www.goldfishparadise.com/forum/phpBB2/
sometimes when the questions are too specific, i'd rather go to a specific forum, but of course that's just me.