Anonymou[b wrote:s]I would call the principal and make sure it's clear in her record that these were all excused absences for medical reasons,[/b] and then to discuss whether there are particular concerns with her school performance that need to be addressed. If it's just a form letter and nothing to worry about, the principal can clarify quickly, but if there are issues, better to be proactive rather than waiting for an actual demand for response.
This is a very good idea -- OP, do this right away. I would want to ask for a copy of whatever portion of the school record says in writing that these were medically excused absences. This is just so that you don't assume, right now, that all these days are listed in your DD's record as excused when possibly that is not the case in the school's records. You just want to ensure there are no surprises later that you then have to go in and ask them to fix. No need to be confrontational about it when you ask; just approach it as, "As part of being sure we're doing all we can both to get her well and to ensure she's keeping up with school, I want to check to be certain her days off sick are officially listed as excused, medical absences." I do know a parent who had to tell the school to change what were listed as some "unexcused" absences because they were actually medical--the parents had let the school know that on those days but it got mis-recorded.
OP, have you talked with her teacher(s) about her work and the impact of the absences, other than just to get homework assignments sent to you? I would involve her teachers and would want to know whether she had, for instance, missed key classes where certain concepts were explained that she just can't pick up through doing homework about them. Maybe her teachers already have this part covered, though.