Looks like an SA Cichlid at first glance but looking at its lip. may be T. moori (pics are not that clear) in terrible condition. How can they sell you fish in such condtion, not to mention how can they keep fish in such condition
If it turns out to be T. moori (very wide color morphs available, from different location of Lake Tang), they are grazer. Do need in good water condition w/ algae diet. DO NOT OVERFEED at any time, should give smaller amount more often. Known to being susceptible with Bloat/Waste Away symptom. Very difficult to treat once has bloat. Used to breed T. moori (kaiser, chimba, moliro, murago, chipimbi, etc). Whenever overfed, usually came down with problem. I believe it has to do with their digeative tract.
Whatever it turns out to be, Hope your fish recovers soon and live happy life with you for long time to come.