My guess is you diluted with AA. Do not inject that solution straight. Further dilute with sterile water, bac, or sodium chloride. I prefer a 5 to 1 ratio of des to sterile water. It will still hurt but not the same as you experienced. You can do the whole pin if that bothers you.
I think I recalled it from dat as well as a few other serum tests done to test the effects of ghrh/ Ghrp combo. I will try to find the literature for you. But it is something I have noticed had no effect on my results either.