Comment by Alsedarna

You'd be surprised how much discomfort people get acclimated to as just being normal and never end up diagnosing until something finally reaches the breaking point to forcing them in to see a doc. If it's been weighing on you for a while, you could probably gently broach it with something to the effect of "Hey man--I know there's no non-awkward way to put this, but I think your body might be digesting its own blood and I was worried about you and wanted to see if you were feeling alright."