You must have hit right in the big of the bone in the shoulder for that to happen. He may be ok, just keep going out and keep a eye open for him. A guy at work was out his first year during archery and he was not schooled the best on range. He drilled a doe right on the shoulder and the arrow broke off right at the B-Head. only blood on very end of arrow just like yours. I think it was his cousin or father in-law shot the same deer six weeks later during gun season and when butchering the deer found the B-Head lodged in shoulder and he said the deer was acting just fine, no sign of injuries of infection on meat. He may end up being ok.