I typically give IM injections into the quad and normally as the needle penetrates the skin you barely feel it. I've done many injections before and if theres pain and blood as I start to penetrate I just pull the needle out, put in different spot nearby and inject there. I could just suck it up and inject anyways but knowing what it normally feels like I choose to find a different spot, no big deal. Anyways, today as I was penetrating the skin it hurt more than usual so pulled the needle out, quite a bit of blood but nothing really to worry about. Picked another spot nearby, again more pain than typical so removed needle and again quite a bit of blood. I tried probably about 6-8x before I finally got a spot that felt normal. I'm talking just about penetrating the skin so less than 1cm deep. This got me wondering... what specifically causes that? Never had so many issues just penetrating the skin like today so it got me wondering. My muscle was relaxed, nothing seemed different today than any other day. Been a week since I last injected into that leg. Sorry for kind of a dumb, not complaining about any kind of pain just trying to understand exactly what happens when this occurs.