What's the Name of That Book??? discussion

I'm trying to find a book I read when I was in middle school, around 2004-2006? It was an older book found at a thrift store, the cover art was similar to the older Babysitter's Club and Sweet Valley High books. The plot was about a teenage girl, I believe she drowned and was on the verge of death. A thread connected her soul to her body, and there was a boy (either a friend or her brother) that was also in a similar situation, I think he was sick. In the end, she chose to switch her thread with the boy's because his was more damaged, basically giving her life for his. The way she fully dies is by (in soul form) walking into the water and "officially" drowning if I remember correctly.

At least parts of this sound like Witch, by Christopher Pike, although I'm not sure about the drowning bit. There's definitely the thread connecting her to her body, and she definitely switches with her best friend in order to save his life.

Wait, I think that's it! I'm gonna do some digging.

I just checked, that's it! Thank you!!

You're welcome!