I'd just like to add this since we're at the stage where you're adding the Epsom salt:
If you can, you should probably pick up the test kits from the other house (I'm guessing this is what you meant earlier) and test the tank he's in now. I know those fish are fine, so I'm sure it is fine, but as we discussed earlier, these tanks have been moved around, and so I'm a little worried about the beneficial bacteria. It's better to be safe than sorry, really.
This treatment should work, if it's going to, within a couple of days from your second dose. The combination of pristine water and the Epsom salt will reduce the bloat/swelling, and if he's constipated at all, relieve that as well.
If, after this time, he's still experiencing problems, we have to look at the fact that he may have some type of bacterial infection and can't fight it on his own because his immune system has been so weakened. At that point, I'd move to a hospital tank and medicate with an antibiotic. The reason for moving him is that this will kill all bacteria, and so it will take out the biological filter.
You could begin medicating him now for this, and some people might advise that. However, since he doesn't have any outward signs of infection, I would wait. That is up to you, of course. Basically, if you don't see any change with the Epsom salt, know that the next course of action would be to medicate him.
I really hope that the Epsom salt does the trick without having to medicate further, and I hope he starts feeling better soon.