Oranda goldfish- possibly Swim Bladder?

If he really cant control his swimming, for example: he'll swim down but cant help but float up or like you said floating about upside down. Sounds like he does have swim bladder. From all that I've read having freshly washed peas pealed and fed to them may help. With my oranda he was doing the same thing after feeding him peas he got better, but I had to help feed him because he couldn't feed himself. I had to hold him and wait for him to open his mouth and put in very tiny pieces of peas little at a time. Because if your oranda cant feed himself he will end up dying.