Convict Cichlid not eating

Question
Hello,

I have a 8-9 year old Convict Cichilid whom I adore and am extremely concerned about.  He has not eaten in over 3 weeks now that I can tell, and he's always been a voracious eater.  I have tested his water, everything is where it should be.  He did this about 3 months ago (not eating for a long time) and he got a large "dent" (not a hole) in his front forehead, reclusive behavior, etc..  I treated him with Melafix for 7 days, religiously changed his water, began adding sea salt as directed and I have even gotten him a heater (his whole life he was fine without any of these things, but I am really trying to help him).  He magically recovered one day, started eating and his dent grew back until it's as if it was never there.  We thought we were in the clear and I went back to a 20% water change every week with a small amount of sea salt to just add back in what I had taken out.

This time he has NO dent, but he looks REALLY off.  He has reclusive behavior, when I come to the tank he hides under rocks, and his color is a bit off.  He is also scratching on rocks and gravel, plants, anything he can reach, but it's not constant.  i have added nothing new, and there is nothing else that I can see, no holes or wounds, nothing that looks strange on him, but I am really afraid we're going to lose him, I mean how long can a fish go without eating?  I am on the 7th day of the Melafix again, and will then do a 25% water change tomorrow, but he is not looking ANY better.  I've asked pet store fish guys, but everyone of them has a different idea and I don't trust any of them.  Most say he could just be at the end of his life, but I read online that Cichlids can live up to 20 years in the wild.  I know I didn't do all the "right" things his whole life, but I would really hate to lose him if there is anything at all that I can do to help him.  He's got such personality and he's really quite large...  i just want to him to go back attacking anything that moves near his tank, digging fun holes, and eating like a shark attacking a seal.  There are no other fish in the tank.

Thank you for your help.

Answer
I would not treat him with malafix unless he has a wound.  I would do a 40-50% water change and see if that helps his flashing behavior. Malafix can eat away at the slime-coat and cause more damage then it cure. There is however, nothing better in my opinion for treating wounds then malafix.  I would change the water and let him be.  If in a couple of days he is not acting any different then I would maybe start  him on a dose of general cure or triple sulfate.  He may be suffering from an internal issue such as a bacterial infection.  It may be that someone has scared him. Happy fish will behave just as you have described after a traumatic event.   Please keep me posted... dave