When my daughter had it (she’s 5 now) I would use a warm rag to wipe her hair enough to get the hair damp, then I would massage coconut oil into her scalp and finally I would use a very fine toothed comb to comb away the dead skin cells. The doctors also have a ointment to help. With her losing that much hair I would definitely take her to the doctor.
RE: My 1 year old is losing her hair to Cradle Cap - all advice welcome!