Large deviation and squint

Hi, my daughter, currently 14 have been diagnosed with strabismus, esotropia accompanied with double vision, early this year. She is currently wearing temporary 3M stick on prism on her glasses. With 25 diopters on her right and 15 diopters on the left. She has a new onset of headache, but other than that no other symptoms. The doctor has scheduled her for an MRI should we go ahead with it? What could be the illness? ++ She has binocular double vision, and has myopia 75 on the left and 200