my son eats my hair

my son is almost three.. when he was 10 months my mom legally ubducted him and he was in her care for 13 days. he came home and started pulling out and eating my hair. we have worked with him to reduce the hair eating ... (great he now sucks his fingers) but really i am worried about the ball of hair in his belly.

i have a mental health worker for him... but does ne one know if i can give him something to help pass the hair in his stool ...

i am very worried about surgery and all the trauma from the hospital