My daughter was four when this started happening to her. She had gorgeous hair that was coming out in handfuls. I took her to the doctor, and they ran several blood tests, checked her thyroid, everything came back normal. We couldn't fighure out what was happening, until the doctor finally asked if she had been under any stress recently. A few weeks earlier, my mom had taken the kids over night and had let them watch Van Helsing (a VERY scary movie). My son had nightmares for a few weeks and my daughter's beautiful hair fell out. I have the same reaction to stress. Maybe that's all it is? Did your doctor run blood tests to make sure that there is really nothing wrong or did he just say it's normal? If he didn't do anything, he doesn't know anything, and I would take my children to a different doctor. Good luck!