For about two days I've had this real bruisy feeling around the side of my neck, shoulder blade and bicep, though there is no signs of bruises. I find it hard to lift my arm, and it feels like my muscles are 'stiff'. I can't recall hurting myself. I should probably note I'm a type 1 diabetic, so I sometimes inject in that bicep - I haven't had this sensation before though.
... and the ones that won't