Discus on side/upside down

My smallest discus, been in the community tank got about 4 months, has been hiding for the last couple of weeks.

sometimes just for a little while and then it comes out and swims around with the breeding pair, and often also with the yellow mellon.

I got home this morning and was adding some more plants/doing a water change, and I noticed that it was nestled into the corner, and not even responding to being touched.

I removed it to the breeding tank that I setup in the garage a few weeks ago, and he was just floating around, being carried on the current in the tank.

I added Discus buffer, and 1ml/7L of water of Big L Poultry wormer.

I don't know what the problem is, except that when he breathes something small and white comes out of his mouth, and then back in as he breathes.
intestinal lining or something?

any help would be great.

cheers.

elliot.

As difficult as it is it sounds like your fish is too far gone. If it is floating around the tank I would put it out of its misery.
MAC

further to this, he went completely dark, except for where he contacted with the floor of the tank.

RIP little fishy.

I'm a bit flumoxed by the whole thing, because I got to admit, it all came on quite quickly, a few days really.

and none of the other fish have a problem. the matured pair that have been spawning every week are fine, and still laying eggs.

I'm in the process of cycling the old 2ft'r in the garage, but I fear I might have to wait a few months, because its pretty warm out there, and the water has crept up as high as 33C in the early afternoon, so I think maybe I'll hold off on putting them in there, just get some plants going in there maybe.. might even be too warm for them, though.

*shrug*