Advice please Parrot fish turning Black???

Hi , i've had a few problems with my parrot fish over the past 10 days or so
, he seems to be back to his normal energy levels , he has suffered from a
fungus growth , which i have medicated for and it seems to be
improving..........But now he seems to be going Black ? , his natural colour
is orange , the last time one of my parrots went that colour they where
about to lay eggs , but this parrot i'm almost certain is a male ? What is
the black colouring he is getting likely to be ? i had noticed a small
amount of black on him around 3 weeks ago , but it appears to be spreading.

I've been quite lucky with my fish over the past 4 years , but this poor
fellow seems to be making up for past good fortune , he's around 2 years old
and i 've had since he was around 2 months old....

The black marking seems to be a mystery to me as there not a fungus i
presume , its his skin that has changed colour.