Hopefully it is just a common infection after being beaten by another cichlid, or just poor water from not being changed often enough, or having too little filtration or over-feeding.
Hopefully it is NOT Malawi Flesh Eating Bacteria.
viewtopic.php?t=487&highlight=flesh
(a prevoius post in this same forum)
If it is Malawi Flesh Eating Bacteria, all the Malawi cichlids in this tank are in danger.
Yes: we need to know the water parameters, pH. amminia,
tank mates, tank size, species, temperature, and all that stuff as soon as possible.