What should i do? i need help. hair breakage?

okay so i have dyed my hair black for 3 months now, i stopped dying it for a month and wanted to go back to my natural color.. well as close to it as i could get, i went to a salon and they stripped my hair of the black, my hair broke. "hair breakage" they continued to dye it and put a light brown on the top. my hair color is now light brown, but i have naturally straight hair nice and smooth and now its rough and broken. the person who did my hair gave me leave in conditioner, but i went home and piled on tons of conditioner on it now. should i sleep with it in? would that help any? my hair has never been like this b4 i have no idea if leaving it in over night will help any.. Help plz?