I was going to say BA if it was the 1st time from the bottle. I agree, it must've been the injection itself.
I think perhaps you were very close to a nerve and that's why you couldn't do the whole inject. I'm surprised you even let the needle keep going in, maybe you didn't feel the initial zing of hitting those damn nerves.
I will say, I've hit nerves maybe a dozen times in my days, all but one were always in the quads. I used to love the quads, now they're bottom on my list along with the glutes (only because they're hard to get to, and incidentally, the glute was the only other time I hit a nerve - left glute).