I pinched the underside of my forearm closing a window, my underside got pinched. There was a pretty big bump, and it has been sensitive to the touch, I put ice on it to bring down the swelling. I didn t think anything of it until I happened to see it in the mirror today, a week later and the whole underside is red and puffed up a little, almost like I broke a blood vessel, the redness is below the pinch spot, and the bump is still there, just not as bad as it was last week. The underside of my arm looks like I laid my arm on a hot stove and burnt it.