Ive never heard of pain occurring with changing of blood type. The bone marrow has basically been killed off by chemo (and radiation if used). Honestly, 7 personal years and thousands of posts on the page, I’ve never heard this. Perhaps, your friend misunderstood the dr.
I really dont know. She told me that the daughter had significant pain with the change. More the blood type change than the transplant itself.
She never really recovered and is extremely disabled.