Holding Eggs. When african cichlids breed, the female will hold the fertilized eggs in her mouth until (and for awhile after) the eggs hatch. The breeding would explain the aggression, and the holding eggs would explain the not eating.
Based on the behavior you described, if she is keeping her mouth closed, and if her lower jaw/chin area is puffed out underneath, she is probably holding eggs.
That is NOT completely inaccurate. I will agree that my statement is not always accurate. However, I did say "usually" which is true. While red male metriaclima estherae DO exist, most of the time females are red and males are blue. That is the standard, anything else is the exception.