Help Turkeys showing no symptoms and then dying !!!!!!!!!!!!

[13 chickens]

Help I have 3 black Spanish poults and 2 royal palm poults and I had 1 older royal palm tom turkey, my tom was showing no symptoms and appeared to be in good health, when I shut him up in the evening he was just fine, but when I went out in the morning to let him out he was dead, this morning when I went to go take care of my younger poults I found one of the royal palm poults having spasms and kicking its legs when I picked it up, he is currently alive and in the past 2 months I have had a phoenix rooster die but he had shown symptoms, and a barred rock hen die mysteriously while having spasms. Is there a way I can help before the rest of my turkeys die, and also I know it wasn't black head because hence the name, Black Head, their heads were not tinted black at all, PLEASE HELP!!!!!!