this is a *complete* guess but if it is the vitamins it could be that now you have them its speeding up the growth of your hair so youre getting more shedding as your hair is growing quicker?
I think hair goes through stages of shedding more hair naturally depending on so many different things, your hormones, the seasons, your health etc. can you see a noticable difference on your head of hair missing?
I dont know if there is a vitamin that if you take too much it will make your hair fall out but there may be someone out there with more knowledge that does.
Its weird, before when I washed my hair I would literally have handfuls coming out but it was normal to me as it did it even if I washed everyday but I still had a thick head of hair (this is before CG) then I had my hair highlighted and had loads less come out although this could be because I did it straighter a lot so was brushing it more so the hair was coming out when I was brushing it not in the shower iykwim?
On an instinct I would say that as you've had a lot of growth its the old hair being pushed out, cos theres 3 stages of the hair cycle some info below:
Each hair follicle lives in a cycle consisting of a long period of growth followed by a relatively short period of rest. During the rest period the hair is still attached to the hair follicle, but it is not growing. After the resting phase the hair is shed and a newer hair begins to grow, thus, starting a new hair growth cycle.
There is a genetic predisposition of each hair follicle to follow a particular pattern of growth and rest. Hair follicles are programmed to stop producing hair and spend more time in the resting stage with the progression of age.
The growth cycle of a hair consists of 3 stages:
1. ANAGEN (GROWING) STAGE
This is the name for the growing period of a hair follicle. The anagen stage for the hair follicles in the scalp typically lasts about 3 to 5 years.
2. CATAGEN (INTERMEDIATE) STAGE
At the end of the growth period, hair follicles prepare themselves for the resting phase. This transition period of a hair follicle from growth to rest is called the catagen stage. This stage of the hair growth cycle usually lasts about 1 to 2 weeks or so. During the catagen phase the deeper portions of the hair follicles start to collapse.
3. TELOGEN (RESTING or SHEDDING) STAGE
This is the resting period of a hair follicle. It is usually 3 to 4 months in length and at the end of this period older hairs that have finished their life will fall out and newer hairs will begin to grow.
The growing (anagen) phase constitutes about 90% (1000 days or more) of the growth cycle of a hair follicle, while intermediate (catagen phase; 10 days) and shedding (telogen phase; 100 days) phases constitute only 10% of it. That is, at a given time, about 10% of hair follicles are in the intermediate and shedding phases; thus, not growing. These hair follicles, however, are randomly distributed over the scalp, so that no bald spots are seen.