Hi all! One of my Friends stated when giving an I'm injection to a patient- the arm seemed to pulsate once. (an area of the skin depressed in for a second). Why does this happen?Also I'm starting flu clinics tomorrow. I don't shoot the needle in like a dart bc I get scared of it going all the way in. I just squeeze the muscle, put the needle in a 90 degree angle n inject. I feel I'd hurt the client if I shoot in like a dart- any suggestions?