My son has to wear white dress shirts to school and he LOVES to play football after school before he changes out of his uniform....I usually find his bloody grass stained shirts rolled up in a ball under his bed, dresser, back seat of my car..point is-I always find them days latter. After trying everything on the market I have found the best stain remover is baking soda, vinegar, and water. I fill a bucket up with my first grade science project and soak his clothes overnight. I also have had lots of success with oxiclean on bleeding fabric. Grandma's spot remover is pretty awesome too.
I hope that you find something to help.