spudgun9mm

hey my dwarf puffer is a fully grown male and was fine till 5 days ago he went totally pail and was not swimming, i put him into my other tank and he recovered some color he has and is still hyperventilating with gills and mouth open and can only swim for a small amount of time before he floats to the bottom, i have given him a tonic salt bath as informed and little has changed, but have noticed the problem is his ( lungs ) the things that inflate when scared, he inflated and deflated fine as a breeder told me as a last resort to try and he has gained his old self back as well as color and can swim longer while the rest still is the same, the lungs have deflated and breathing a little slower can anyone help? have suggestions? or know what is wrong ? can post pics if it helps