In Massachusetts, call the Federation for Children with Special Needs. Also the federal Dept. of Education, Office for Civil Rights can be extremely helpful. You can find numbers online. Just call. The latter will come to the school to “educate” them so you don’t have to file a formal complaint.
I had two kids requiring accommodations in high school. Publics, but I did have to consult with the organizations/agencies above and, once, for an hour a lawyer, not for complaints but for ideas.
Tutors wouldn’t really work because the timing of their arrival might not coincide with the best time for my child in a given day. We saw the lawyer for suggestions on how to handle her in and out pattern with school. We made a sheet with headings such as “homework assigned,” “work done in class today”, “tests or quizzes,” “missing grades” and any class materials, notes or even tests were attached to the sheet. The teachers filled this sheet out whether she was there or not so they didn’t have to notice. I picked it up at the school at the end of the day. This way, my kid could go up for a class, come home, go up for two classes and so on. We also arranged for continuation of extracurriculars like music whether my child attended that day or not, for the purpose of social development.
My other kid left senior year by choice, not for reasons of health, but due to an extracurricular performance area that she was pursuing. She got a GED and then a diploma later from an outfit that collects credits on paper, has a few requirements in addition to the usual ones she already had, and then gives a ciploma by mail. Not a mill.
There are other organizations, used for homeschooling for instance, as well as dual enrollment options at community college, which this child made us of as well.
There are several ways to go with this situation, but some of them needed to happen earlier for her to stay with her class. i’ll pm you and will add a little more later.