Is Kidney Stones a good reason to miss school?

If you are completely okay besides kidney stones, then no, you should be in school. But if you still are having the other issues that you mentioned then you shouldn't worry about going to school. I don't think you can p the grade though without coming to a minimum amount of school whether you have doctor's notes or not. If you are as sick as consistently as you are, you won't p the cles no matter what your grades actually are.