goldfish is ill!!

Question
Hello, I have a 150 gallon freshwater tank. I have 4 gold fish, none bigger then 2.5 inches. It is a fairly new setup, and they are fairly new fish. the largets of my goldfish has taken to sitting on the bottom or hideing in a cave for several days now. He can swin just fine when he wants to, which is pretty much only when i feed them. Then yesterday it seemd my second biggest one was wantingto hang out down there too. So Im fasting them, as I think they are constipated. I just recently learned that flakes should only be PART of a healthy diet for them. So, I fed them pes yesterday, and nothing sence. They all seem fine, except for the biggest one. He is getting huge over night. He is swelled, and not just his belly, I mean swelled all over. He looks like he has a double chin almost! And then, I nthe cave where hes been hideing, there was a yellowish blob sitting on the gravel! Slightly larger then a pea. its gone now... I have no idea hwat is going on with this fish. Also, the water has been tested and is all ok. the other fish are fine. Is he suffering, shoudl I end it? Canhe be saved???
~sam

Answer
Is there also scales protruding as well? If so, it's dropsy and you can cure that by feeding the sick fish anti-bacteria medicated fish food. If not, please email me the following pictures (if possible):
zoom in of fish
zoom in of trouble areas
area of tank they are in the most
you can email me at megan140@msn.com