Sick Discus

[Hammerboni]

I bought this discus on Sunday and it was doing fine until I made a water change earlier today. My tank is at a 7.0 ph and is at 86 degrees. After the water change the water temp went up slightly to around 88 but the ph stayed the same. I don't believe it this happened because of the water change. I think it was just a coincidence it happened today. It is getting worse and starting to effect the the other discus in the tank. Please help me out ASAP thank you so much

 

[Delapool]

How's he doing?

Different fish but I've got platys that don't seem to like water changes at all.

 

[treemanone2003]

Wish I had seen this earlier. I'm with you it's not a result of the WC. Your fish is stressed for some reason and appears to be losing its slime coat. Discus require LOTS of water changes and excellent water quality. Some basics before going any further.
What size tank ?
Other tank mates ?
Other water parameters ?
Did you QT this before adding ? (From what you stated it doesn't sound like it)
Are you treating the water ?
Parameters if water right from the tap ?
Appears planted.

Edit : Discus do best in 10-15 gallons per fish and is recommended for a min of 75 gal.