Couple discus acting unusual. Advice needed.

[Camden]

I have a discus that is showing abnormal signs of fins clamped against his body, stress bars showing, but his appetite is normal. He faces the back of the tank often and rarely schools with the other fish. The water parameters are normal. 0 nitrates 0 nitrite 150 ppm hardness, 130ish Alkalinity, 7.8 ph.
Just curious what could be causing this behavior. I haven't yet seen his feces.
http://i104.photobucket.com/albums/m191/Gamdian/IMGP0772.jpg
pic of him

Alright I also am having another problem. I had two adults I thought were pairing up so I moved them to a 30 gallon to see what would come of it. Now I see whiteish stringy poo trailing behind one. I'm pretty sure that's a sign of Hex. But wanted to make sure. The other I noticed today has a mark on his side that wasn't there yesterday. Water Para are the same as above tank.
http://i104.photobucket.com/albums/m191/Gamdian/IMGP0757.jpg
above is the mark one.
http://i104.photobucket.com/albums/m191/Gamdian/IMGP0763.jpg
http://i104.photobucket.com/albums/m191/Gamdian/IMGP0762.jpg
http://i104.photobucket.com/albums/m191/Gamdian/IMGP0761.jpg
white stringy poo guy/gal.

I'm really stressed out about these guys. All this happening at once is a bit of shock to my system my poor babies...Any help comments or questions will be much appreciated

[pcsb23]

Always difficult to be 100% certain, but I would suspect flagellates at this time.

You seem to have a varied mix of different fish in the main tank, stress is one of the major causes of flagellates getting a hold.

The mark on the side of the other discus may just be from when you netted/moved it. Clean water should be all that needs.

How many fish are left in the main tank?? discus prefer groups and if that is disrupted can cause stress, however the symptoms indicate possible flagellates (and a few other things too!)

[Camden]

How many fish are left in the main tank?? discus prefer groups and if that is disrupted can cause stress, however the symptoms indicate possible flagellates (and a few other things too!)
The main tank has 6 small discus about 3 inch in size and the large guy showing the stress bars and abnormal behavior. The chiense bat fish is the only guy in the main tank that isn't a discus and I keep him in there because he does a great job keeping my sand clean. If it is Flagellates (in the pair tank), I should treat with metronidazole no? What dose do you recommend? Thanks for the reply Paul !