Well if you ment to say 10IU bottles mixed with 1cc of bac water then this is my take.

As long as he is pinching a piece of fat on the belly area and using a small Slin pin then-

The .9% of benzoyl alcohol in the back water might of given him a localized reaction. Have him inject 4 or 5 IU's of bac water with no GH in it and see what happens. If he gets a welt then he must switch to straight steril water (which GH only is good for about 5 days in)
But
If he doesn't get a welt then it could be the GH or some additive that was put in it. Tell the source that they came from and see if they can help. In the end it's the very true saying "know your sources". After testing with trial-and-error stay with what works.

Best of luck bro.