I had the same thing happen to me a few years ago. Like you I went to a dermatologist and was told the same thing. I was put on biotin forte, which did not work! I also spent alot of money on products to try and stop this process from continuing. Nothing worked, the hair kept falling out and my head had a burning sensation 24 hrs a day!
I found out about a safe therapy called laser hair therapy and finally got my hair back within 4 months and also stopped the burning sensations. That is the advice I would give to you, to find an establishment in your area that offers this service. I would not buy the comb though because it is a cheap home method that is not going to work. Stick with the large clinical machines and get the treatments at a place that offers them.