HI, My Daughter Is 8 Years Old, But She Has

HI, my daughter is 8 years old, but she has severe asthma. She's currently on prednisone when she has an attack, but has needed it every day for the past month. She is aalso on advair 100/50, xopenex nebs when needed, singulair 10 mg, and xolair shots. She's been needing the neb 10 or more times a day. SHe needs a few at night, and many at school. Her doc wants to up her to 500/50 advair. Is this safe? What else can I do? Her best peak flow is only 110.