State law requires that all children over six attend school unless they are ill and unable to attend. Often a note from a doctor is required for extended absences. It is not unreasonable for a district to inquire about the nature of the illness to verify that an excusable illness is involved. I am sure the district would accept a doctor's note if you are reluctant to discuss the nature of the illness. You can refuse to supply any information but the district might treat as an unexcused absence.