The fish looks like a juvie Kenyi (Maylandia/Metriaclima lombardoi). If the fish stays the blue and white stripes then it is a female. If it develops a strong yellow color then it's male.
As for the brown bump I would have thought it was a wound until you said it was a bump. Do you think it looks like scar tissue from a wound? It could be a burn from the heater.
Also, have you checked parameters? It could be a chemical burn from either ammonia or chlorine/chloramine.
Check those possibilities and let us know what you find.
P.S. Welcome to the forum!