In nature, approximately 50% (maybe more) of Texas cichlids diet is algae, and detritus (they are omnivores, not strict carnivores).
Could be yours is not getting enough of that roughage, and getting to much meaty type food, that stalls in the digestive tract, allowing the wrong kind of bacteria to proliferate.
I find giving most members of the Herichthys clade a low protein, high in algae (Spirulina) pellet may be a better regime than if your relying on lots of protein like shrimp, bloodworms or krill.