puzzled about my goldfish swimbladder thing...

Hi

Having starved one of my orandas for 3 days then feeding it boiled
de-skinned shredded peas for another 3 days, the moment i put it back
in the main tank, after several minutes, it starts floating up to the
top again ( even thou i even haven't fed it anything yet!!). i've
tried all that advice from people in the forum but never works. the
oranda's still floating up to the surface with a bloated tummy after
feeding time.
JOHN