you could try a mix of melafix and pimafix, both mixed make for a pretty strong medicine
if it is indeed a swim bladder problem, try feeding thawed peas cut up into small chunks, as well as some green leaf luttuce, maybe even some spinach
and it you can find small pellets, try that also, or even slow sinking sticks
i never tried any of this stuff for mine, but its what my father reccomended when mine had it, unfotunately they died befor i could even begin any type of medication, or change of diet
what is your PH, and hardness at?