What length needles are you using? if you are relatively lean try to use a 1 inch instead of 1 1/2. Also, directly after you inject it, use the soft part of your fist and pound on it for about a minute or so, then message for the same time. I too felt the kind of pain you are describing and after using 1 inchers and the methods i said above the pain was miniscule compared to before.
drago
drago