First... talk to the school.
Our school's policy is 10 days per semester (even with medical purposes). Our daughter was out sick last spring which put her in jeopardy. She was in 10th grade at the time, all Honors student, cheerleader and great grades.
Each time she was absent, I contacted each teacher for assignments.
I went to the administration, provided all the Dr. notes AND bills where it was clear that she was sick and not just sitting out becuase she didn't feel well a day or 2.
When honest parents do this, administration makes exceptions. It is those who simply blow off school who end up repeating the grade.. they tend to be the ones who routinely cut school and face truancy, parents are not involved much or at all or just look at the school as a babysitter, they tend to not like school, not do well socially or academically and are pretty immature for their age, hence.. REPEAT the grade.
My daughter's friend had an awful bout with mono and missed woefully more than the 10 days per semester. They did the same thing we did, provide the hospital bill along with all the other bills and Dr. notes and she was also sent on to 11th grade.
I would talk to administration now so they have a heads up and know what is going on now vs waiting until they send you the truancy letter and tell you that credits will be lost due to being absent.
Good luck..