Unfortunately, it could be early signs of Alopecia. When hair is constantly pulled back in the same way for a long time, it can cause temporary hair loss. The good news is that because she is so young, it can definitely grow back. You just need to give the braiding a break until her hair grows back and is strong enough again. There are many products on the market for thinning hair, such as REDKEN IntraForce Shampoo (R210), Conditoner (R242) and the Scalp treatment that stimulates hair growth (R279). L’Oreal Aminexil NISIM Tripac Shampoo, Conditioner and Extract (R980).
Hope this helps!