Mom seeking school help for 18 year old daughter

My 18 year old daughter is really struggling with school to the point of being physically sick on a daily basis. She has some medical problems that are contributing to this as well. (She is seeing a counselor and a medical physician.)
There is no way for her to get enough credits to graduate. What I am looking for is a high school diploma program or possibly a home school program. Has anyone else had good/bad experiences with this? I really would like her to get a high school diploma and there's a lot of programs that I found information about on the internet, but wanted to see if anyone has had any personal experience with this. Any recommendations would be greatly appreciated.
Thanks!