Welcome to the boards. I know you'll find lots of answers, opinions, motivation and friendship here.
When I did the Quick Weight Loss Program many years ago I had the same problem with massive hair loss. I was told at the time that it was due to the almost NO fat diet. Once I added a little fat back into the diet, I stopped the hair loss and now have my full head of hair back.
I don't know what plan you're following, but you can/should have some fat in your diet. Besides giving you healthy hair and skin, it helps the metabolism function.
Check around by reading some threads. I'm sure you'll find a happy home here. Everyone is very kind here.
Hope this helps.