African cichlid with lump on head

Question
Tank set up almost two years.
29 tall.
Pale blue mature African Cichlid, two healthy plecostemus, one peacock eel.
Magnum 300 HOT w/bio-wheel.
pH/ammonia/nitrite acceptable.
(partner does these, his answer).
Change 10 gallons monthly.
The cichlid is at least 3 1/2 years old. (Given to us about two years ago, with three other cichlids. He killed them over a year ago.)
Developed a sore on one cheek about three weeks ago. last week, a new sore on opposite cheek. Lump growing slowly between eyes for a while. We didn't really notice it at first. Last week, big open sore on lump. Took photos to fish store, got PimaFix for tank. Treating for one week. Sores are healing, but lump is growing fast. Looks like a lot of little cysts now. Fish is slowing down a little, but still zooms around tank and eats. Picks on plecos. No flashing or running into things.

Answer
Dear Kathie, Sorry to hear about your Cichlid.
Indentifying a mysterious bump or skin growth on any fish is very difficult. But I can try to offer a few suggestions.
-Nodular disease causes off white to yellowish cysts anywhere on a fishes body, and is caused by various Microsporidian and Myxosporidian Parasites. The life cycles of these parasites are poorly understood. Small level infestations may occur unnoticed by the aquarist. Unfortunately there is no reliable treatment for this type of disease. It is best recommended to isolate the infected fish to prevent any spread to the others.
Now I'm definitely not saying this is what your African Cichlid has but it is only a guess.
I have never dealt with this disease so I cannot say for sure.
-Lymphocystis is caused by a viral infection and symptoms are characterised by raspberry or cauliflower like growths on the skin and fins. It often begins as small white cysts which gradually increase in size over weeks or even months.
-Fish pox is a viral infection causing white, grey, or pink growths appear on the skin and fins. They can appear as small waxy-like growths or bumps on the skin. It is sometimes confused with Lymphocystis but it has a rougher raspberry like growth to it. Fish pox has no reliable treatment this disease most often affects coldwater aquarium and pond fish, in particular, Koi. There is no reliable treatment. I really don't think this is what is affecting your African cichlid. Like I've mentioned before, these are all just guesses.
-Tumors are something I've dealt with before and they of course cause swellings similar to what you described. The fish may behave naturally for quite a while. Then the tumor may cause the poor thing to suffer or it may cause organ failure and end the poor fish's life early. Unfortunately as you know there is no treatment for this illness. The best you can do is give the fish the very best care possible and try to make him as comfortable as possible.

Because it is so hard to know exactly what is ailing your African cichlid I can only recommend that to continue with the pimafix (Melafix may be better since it tends to target bacterial infections or sores better than Pimafix which tends to target fungus infections) Using these two medications together will give the most effective treatment. Also, I would begin daily to at least every other day 50% water changes as part of the treatment. I tell you, there is nothing better that you can do for a fish than good water changes. Make sure the temperature is suitable for his species and feed him the best and healthiest food possible. Variety also is important of course.

I really hope this helps! The fact that your African cichlid is still eats and enjoys picking on your plecos may give some good hope that he might recover!

Best wishes and Happy Holidays!
Karen~