I hesitate to suggest this BUT, If the pain is from the BA content and not from contamination, READ THAT AS A BIG BUT, you might try adding a little, AND I MEAN A LITTLE, lidocaine to the solution. It will make the area numb so you don't feel the pain. But if you use to much YOU WILL DIE!!!!!!!!
You can get injectable lidocaine, its sold as Xylocaine. If you go that way I would load the syringe with the gear then add the Xylocaine so it goes in first. It will burn for a moment then be numb.
But if this gear is contaminated you will be in BIG TROUBLE!! You will get an out of control infection. And when the lidocaine wears off only morphine will help you until you DIE!!!
Did I mention that you might DIE!!!!