How to get mysterious brown stains out of white?

[Skywalker]

I have a white hoodie which was absolutely stain-free. It got put in the wash with the other white items and when it came out it had three brown stains on the hood which were most definitely never there before, and I have no idea what they could be. And they're not surface stains; they look like coffee stains that have gotten completely embedded in the fabric. I don't know how this happened because my mother did the laundry, not me. The irony is that it got put in the wash to be cleaned and came out with stains. I don't want to use bleach because I've heard it can yellow white garments. There are also of those ironed-on prints all over the hoodie (which are all light blue) and I'm scared they could get damaged from the bleach. Any help, please? I've heard bug spray can help, but seeing as my mother told me this and she got the stains on in the first place, I don't want to try that.