I have no idea about "pepper suppression". I'd immediately order the Metronidazole to treat the turks & pick up some Safeguard for worming of all poultry on property.
I believe dosing/info on worming in provided in thread linked to however, check casportpony's posts in this thread (is well...
This thread will provide good info. on meds required for treatment of Histomoniasis ("blackhead"), along with info on worming entire flock:
https://www.backyardchickens.com/t/804570/coping-with-blackhead
They can get "depressed" and mope about for days, but that is almost always the result of losing a sparring match with another tom (not your problem). I'd separate him out immediately and start keeping an eye on food intake & droppings. Could be a change in the weather, but I'd suspect he...