Where did this come from?

Funny thing about writing. They say that the author shouldn’t really be in control of the story, they should just let the story flow from them, and not worry about plot points, character description, and whether it’s going in the direction you predicted, you should just write what you see, what the story tells you to.In Black Hole Son, the main character is going though his sole possessions and has found a fuzzy pink sweater. I do NOT KNOW where this pink fuzzy sweater came from. I planned for everything he had, but this. I only know that in my mind’s eye, I saw that in his bag, he had a sort of gun, but the gun was lying on top of something pink. It seemed like I should describe exactly what I see, so I included it as a fuzzy pink sweater. So now he has one. The thing is I don’t know how it’s supposed to figure in, since these are objects that are supposed to clue him into his past. There’s nothing in the bag that I didn’t plan for, except that. So I don’t know what to do with the pink sweater, it’s the most out of place thing. And it keeps coming up, because he’s trying to find the significance of it too. I think this means I’m doing it right.