HITH/HLLE would be my guess.
metro and clean water.. vary the diet as this has been associated with lack of nutrition.
Flagellated protozoa have been associated with cases of HITH but not with HLLE.
IME, HITH /HLLE is a problem some cichlids may run into.. some seem to have more resistance to it. while others more susceptible.
I agree. http://www.pondcare.com/Products/TechSheet.aspx?TechSheetID=7 says clout is a good medication. The earlier you catch it the better. The water in your pics seems to have a lot of particulate matter floating around. What are the water paramaters? You said your tanks is finally stable.