I would try co-washing. I haven't used black soap, but that could be a big contributor right there. Have you ever laid off the black soap for a couple of weeks to see what would happen? Also, sorry I don't know all the ingredients here, but I know that I have extreme dryness when I use products with silicones. My hair hates them. It will be soft and silky while wet and then SUPER dry once it dries. I would keep applying more and more conditioners (not realizing that the silicones in the conditioners were doing more harm than good) and the problem would just get worse.
Sorry if this is all stuff you've tried already...good luck!