Hole in the head disease or Head and lateral line disease.
It's common in cichlids kept in dirty environments and allows a parasite called Hexamita to infect them.
Wipe the inside of the glass down with a clean fish sponge.
Do a 75% water change and gravel clean the substrate every day for a week or two.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.
Clean the filter if it hasn't been done in the last 2 weeks. Wash the media/ materials in a bucket of tank water and re-use them. Tip the dirty water on the garden/ lawn.
Add 2 heaped tablespoons of rock salt, sea salt, or swimming pool salt for every 20 litres (5 gallons) of tank water. Keep the salt in there for 2 weeks.
When you do water changes, add salt to the new water before adding it to the tank so the salinity (salt level) remains stable.
If it hasn't improved after that, get some Metronidazole to treat them.
API General Cure contains Metronidazole.
