We've seen this before Woodsie. It looks very dramatic, but it will eventually resolve, although it may take a very long time. It's a pity, because he's a good looking fish.
Thirty-five years keeping and breeding discus, and I'm still learning :P
Its very slowly starting to fade now, hasn't slowed him down any just looks dreadful. Must have hurt, even his eye on that side went black. Now he has a red eye again. Yup lost all the colour on that side (went to a really washed out blue)
Before you judge a man, walk a mile in his shoes; after that, who cares?! He's a mile away and you've got his shoes!