I would set up a QT and bring him inside. He may have a swim bladder problem. I'd get a big sterilite container from WalMart (10 - 15 gallon or bigger) put a filter on it for O2, a small heater if your house is cold. Bring his Black Moor friend inside, too, to help him not suffer stress from loneliness.
If he is rolling over then you need to help him with this. He may be constipated. Some peeled, nuked, frozen english peas are great for this. If he is having trouble staying upright and is floating up so his belly is at the surface of the water, then a soft breeder net to lay in like a hammock can help until you can get this under control.
The bump, I'm not sure what this is. You really will have to try to take pictures, but that would be easier once you have him in a QT indoors.
The water in the QT must be kept pristine so this means daily huge water changes, since goldies are so messy. A good dechlorinator that also helps to keep the parameters safer is PRIME. It removes chlorine and chloramines, but it also detoxifies ammonia and nitrites, which will surely start to build up in the sterilite tank. (not the nitrites really in an uncycled QT, but the ammonia will start to climb)
Even using Prime you still must do daily big water changes with dechlorinated, temperature matched water.
I have used a sterilite tub as a hospital tank many times. It is easy to keep clean, but you do need to run a filter in it. If we decide he needs meds then the carbon can come out, but the filtration with a foam block or poly in it will help with keeping the particulates down. A bubbler would be good, as well.
Post as soon as you can to let us know how he's doing. We want to help in any way we can, but, really, we're sort of flying blind without more information and pictures.
Wishing good thoughts for you and your little friends.