Pictures would help if you can get them. Are the white balls kind of fuzzy or do they look more like pimples? Are they round or patchy or does it look like they have a thread-like tail coming from them?
If it looks like tiny little white pimples, it could be the start of
ICH. As they get bigger, they look a little fuzzy. Without pics, it is hard to be sure.
Unfortunately, ich is a big problem with
goldfish since they are such high waste producers. The stress of moving from the 'breeder' to the store, being in too small or too crowded tanks, then the stress of moving to their new home and being in a small quarantine tank - it lowers their resistance. Melafix is a fairly good, all around medication for goldfish. Ich Attack is another one that works well with goldies.