Discontinue the bloodworms, an exclusive bloodworm diet can quickly lead to the malawi bloat in algae-grazing mbuna species such as red zebra's.
Try introducing only veggie flakes or sinking low-protein percentage pellets. In time hunger will compel this red zebra to eat them as Mouth-Brooder-Fanatic suggested. If rejected, just try again the next day and the next rather than providing bloodworms.
Her stomach doesn't appear to be overly sunken in.
Rift Lake and Reef tanks.