Bruce, infections (if that were actually the problem) can arise and kill somebody in a week or less. If you follow sterile injection procedures, you shouldn't be too worried.

If your injectin spot is rock hard, hot, red and painful, AND your temp is high/you feel sick, then by all means, get to the doc! If it's just painful, hard, and a little hot with no accompanying sickness, you might be ok.

This is a touchy one, and you had better just remember that you'd rather be smart than dead...