Discus lost color and thin

[jpancal]

So I woke up this morning and went to feed my discus. Everyone ran up front to be feed. Except my sunset discus. I all of a sudden notice it had lost color and looked very thin. Know that I think it about it it looked a little lighter in color yesterday but not as much as today.
It is usually the shy one in the group to go up to get food. Usually when I walk away from the tank it will start eating. So I didn't notice it not eating until today. I realized it hasn't been eating because it looked very thin. I don't know why I just noticed this today; all of a sudden it looked like it lost all this weight.
I have been studying for exams and finals and haven’t been paying as much attention to the tank I would like and now I feel guilty.
Anyone know what I'm dealing with? None of my other discus are showing symptoms. All levels are in my tank are constant and within normal limits.

[Jennie]

Could be any number of issues, internal, external, bullying..etc got a pic? Get qt tank set up

[jpancal]

I don't have any pictures. I havn't even had time to take any and upload them. He just looks very thing and hes not eating.
What are some conditions that could do this?

[hedut]

I don't have any pictures. I havn't even had time to take any and upload them. He just looks very thing and hes not eating.
What are some conditions that could do this?

Many thing bro, could be hex or could worst . pic will help a lot :) and how's the "pub"?

[Eddie]

As other mentioned, could be different things. Worming the group would'nt be a bad idea IMO.