? Bruise from large needle? (Adequan or b12)

is this a bruise? I have no idea. This is indeed at the injection site for mr b's adequan, which he had last friday. initially i thougt it was staining from his b12 shot cuz its that color, but that shot was 2 wks ago and i dont know if it would stain. Would it? I just happpened to notice this today. Sorry not a great pic.

Anyone? Those adequan needles are large and the liquid is viscuous. I'm thinking its that, as i do feel resistance when i insert needle . Not like insulin needles!