The swim bladder is the organ which allows a fish to stay at any level in the water column without sinking or floating. The swim bladder may fail from damage by bacteria, parasites, genetic faults, or blows and/or bruises. When the swim bladder fails to function the fish loses it's ability to swim normally and may swim sideways or even upside down. Once damaged, the bladder does not usually return to normal function, but if the fish can eat and swim without too much strain it can live for years with the condition. Goldfish seem particularly prone to swim bladder problems. Without knowing the exact cause of the malfunction, treatment is difficult. Since internal bacteria, fungus, or parasites are the only treatable causes, medicated food and/or antibiotics should be tried along with frequent water changes. ==========================================
Did not mention the treatment but will investigate...
It is a possibilty, however my personal expirence would suggest that its very uncommon and thats why i didnt suggest it.
In terms of treatment, the swimbladder has very poor blood supply to it, so any meds will be unlikely to even get to the swimbladder, anti-biotics would better than over the counter treatments, however i like using them and i defiently dont like to recommond them as;
a)they expensive b)hard to obtain c)very hard and risky to admister.
However like i say you willnt know truely until the weather picks up.