Do you have the ability to post a photo of him and his comb?
If this came on suddenly, if he was fine just yesterday, if you didn't notice any black spots on his comb yesterday, then I am going to guess he got a good ass-whooping from another rooster who is higher ranking.
The black spots, if uneven, some small, some large and irregularly shaped, it would fit into a fight with another roo. In these fights between two roosters, the loser often sulks in an out-of-the-way place to make himself invisible to the roo that did this to him.
If I'm right, he will probably recover his ego, and return to normal behavior tomorrow.