IEP - Individual education plan. Because the student is not learning to grade level and needs individualized help in order to pass and catch up. 504 - the student is needing supports from school but not necessarily educationally based (like medical from nurse, or counseling from counselor or LSSP or whatever, ST, OT, PT, you get the idea)
Any time you have a student that you see fairly often and they have an IEP or 504 in place, a nursing care plan needs to be drawn up. This is the IHP - Individualized health plan. One for each diagnosis the student carries and needs nursing care for. Example: ADHD, Emotional Disturbance, Anxiety or Diabetes, Seizures, Encopresis, etc.
Essentially it is like writing a care plan if in the hospital (back before computers generated them).
Good luck! I wrote all of mine last week. Nearly 40 of them. Every one of my students has an IEP and several diagnoses that we work with.