Oh man. I ask my kids to crack my back all the time (big strong teenage boys) and wonder if I could get hurt. Guess you can. It is doubtful anything major is wrong but instead a pinched nerve. This can happen when you do the 'crack' to quickly or forcefully. They gave you the shot and some pain releif but I'd add some stretching to it. You want it to naturally heal. So, rest it, ice it, use heat, all of that. I like Salon Pas and put those on when in pain. Icy Hot does the the trick too and comes in a cream. If it hurts after another week, go to your general doctor (not urgent care). But bet it gets better. https://www.medicalnewstoday.com/articles/back-cracking