Looking for a story I read here that had like 9 chapters, old man gets in auto accident and ends up in boys body, goes through different reincarnations always trying to get back together with his friends. In the first story he has a relationship with his mother. Lot's of brain damage, always using money to help people.
I think it may be this one you're after:
https://storiesonline.net/s/74205/the-methuselah-complex
While "The Methuselah Complex" is an enjoyable read Elawn is probably correct as there is no brain damage and no mother/son incest in the story you linked.
Furthermore "Second Chance" fits the description very well.
