"I'm young, I don't care!" LOL LOL Sorry, just had to add that one in. I quote SD!
I think it was from me banging something during some sort of workout. I do have lots of food with iron and take multivitamins once in a while. I did see a doctor once and did loads of blood test to find that all levels/cells are normal.
ADD: I probably earn them too, but boy oh boy do they look like you've been abused.