*HELP!* Fantail Goldfish has floating problem

[TypeSDragoon]

for over a week now, my 4 year old fantail goldfish has some weir floating problem, as if he has helium inside of him.

he struggles to swim down and when he stops he immediatly shoots upward to the water level. he just can't stay below the water level

for the first few days he was upright and just floating at the top with his top fin kinda sticking out of the water, but the last couple days he is completely upside down and cannot correct himself.

no matter what he does, he floats instantly to the top upside down.

since his underbelly has been above the water level for a couple days it has turned very blood red.

the petsmart people told me to feed him chopped up frozen peas, but that did nothing.

thanks for any advice

 

[TypeSDragoon]

he looks perfectly fine except for the redness now on the bottom because of it being out of water when upside down.

he won't eat the peas because he's too busy floating upside down and struggling to go under water