I have oily hair which is not a problem. In july of this year I woke up and my head was very wet at the back, it started to itch and flake a lot. The patches on my head became so bad some of my hair fell out. I was given Nizarol, it cleared it, then came back a few weeks later. Can this be due to bad water, or using too much Dettol, or sun, I live in Africa.