As to why your hair is falling out, there can be many reasons, already addressed here. If you are near the age of menopause, hair will often start to fall out, then grow in again later (hopefully!). Also, permanent haircoloring products can cause hair loss.
I am near menopause, and started losing a lot of hair, to the point of beginning to see a bare spot on top of my head (which was really horrifying--I thought I might be going completely bald!). So I started taking a high potency multi-vitamin/mineral supplement, and I tried a product called Tricomin (do a search to find it on the net). I use the shampoo, conditioner and spray-on solution. I first started noticing that my hair was growing faster than usual. Then after about 3 months of use, I can now say that my "bare" spot is pretty much gone, and my hair is thicker all over. I'm also not losing nearly as many hairs daily as I was.
I don't know if it was the Tricomin, or the vitamins (or both). I read an independent report on various hair "regrowth" products, and Tricomin was listed as one that really does seem to work well, for women anyway. Many men have not had such good results with it.
Also, the nutritional supplements Biotin and Silica are both supposed to help hair grow. You might want to take them in addition to a good multiple vitamin/mineral supplement. Good luck to you.