Hair falling out ?

So, my hair is naturally thick. My hair used to fall out like normal. They say your hair falls out at an average of 100 strands a day. Today, this morning, I was in the shower & had just put shampoo in & was washing it out, when clumps of my hair came out. I didn't freak because of the average thing, but when I put conditioner in, it kept coming out. Still didn't freak, but when I started brushing & drying off, so much more came out. I was asked about stress, but I'm not stressing, I am only 13, almost 14, and this is scaring me. I used to have very long hair, but when it was just regularly falling out, I got it cut in fear of this happening. Now it's a little under my shoulders. I have a history of thyroid in my family, but am way to scared to go to the doctor; blood work. So if anyone would have any suggestions, that would be so nice right now.