I would suggest raising your temp at least 3 more degrees to 83.
Discus have weak immune systems compared to many of the other tropical fish, so they can pick up diseases that other fish show no symptoms to.
Are you sure that your tanks are cycled? If your ammonia was a little high it does not sound like it was. If you did not place any fish food in your tank for that month it was set up, most likely there is very little bacteria to convert the ammonia.
How often do you do water changes? Discus need very clean water. I have mine in a barebottom tank, vac and water change twice a week.
When you say it looks like they skinned themselves, it sounds like the Discus Plague. I read in a fish magazine not that long ago how Jack Wattley cured his fish when they got it. No meds work in curing them. He lowered the PH in his tanks every couple of hours till it was about a PH of 5. At a low PH viruses and bacteria do not multiple and start to die. He kept the PH there for a few days and the fish recovered. Maybe do a google search and see what you can find on Discus Plague.