Ok...lets start simple here...
First of all, all fish have a swim bladder. It stops them either sinking or floating, according to how much gas there is in it. There's no such thing as 'swimmer's bladder', or even 'swim bladder disease', in the same way there's no human disease called 'stomch ache'; it's a symptom of something else.
It doesn't sound like your tank is cycled (ie, it doesn't yet have enough good bacteria living in the filter to eat the fish's wastes), so you need to do some big water changes until you can get your water tested for ammonia and nitrite.
I'd suggest you buy yourself kits for those (and get liquid or tablet based ones, not the paper dip strips, they're not very accurate) rather than rely on your LFS (local fish shop). If you do have your shop test the water for you, it's most important that you right down the actual numbers and don't just let the shop tell you 'it's fine', but you rely do need tests of your own.
In the meantime, drain nearly all the water out of the tank, leaving just enough for the fish to swim upright, and refill with temperature matched, dechlorinated water. Don't forget to switch your filter and heater off first! That should get rid of the toxins that are building up (from the fish's poo and wee) and poisoning the fish.
You will probably need to do at least a 50% water change every day for the next few weeks, unless you can get hold of some already cycled filter media (that's the sponges or whatever is inside the filter). Your shop might give you some if you ask, or do you have any friends with tanks, or even ponds, that might help you out?
