For starters, no chiro should lay his hands on your to do any adjusting (or anything else) unless he has your current x-rays and an MRI in hand.
That said, I am a bit biased....a chiro nearly crippled me permanently last April. I'd had back pain pretty bad my whole life, but it started to get unbearable. Like unable to drive, walk for more than a few feet, sit for extended periods, etc. Tried an epidural which worked geat until it wore off a week later.
Out of desperation I went to a chiro. Even had my current x-rays in hand. He said my spine "looked terrific" and said it was a messed up periformis muscle. Did some massage stuff that hurt like a you-know-what and then did some adjustments to my back and leg (specifically tugging on my legs). When he did that, I felt a sharp pain in my buttocks, and when about 1/2 and hour later, the pan became extruciating and my whole right leg went numb. I was terrified. I couldn't stand for more than a second before I had to get on my hands and knees to alleviate the pain. I couldn't walk. I had to crawl around my house....crying.
So I called his office and they assured me that "it was completely normal" and that it was just my nerves "waking up". WAKING UP?? I couldn't feel my leg!
I mentioned it to a friend (who's husban is a pain doctor) and she freaked out and had her husband order me an immediate MRI (the next day). DH took me for the MRI (I couldn't drive, and cried the whole way). I asked how long it would be for the results and the tech said 24-48 hours.
AN HOUR LATER, my friend's hubby calls me and says "DO NOT MOVE. Stay still as much as possible on the couch. I'm making you an emergency consult with a surgeon". He had spoken to the tech and read my MRI and found a massively herniated disc.
I went to the surgeon the next day who agreed with the assessment and admitted me in for surgery 5 days later (it was Easter weekend). I called the chiro's office to tell them I wouldn't be coming back and they started panicking and demanding I bring them the MRI.
Fast forward...when I woke up from surgery I was 95% pain free and the surgeon was standing there with a little jar that had my exploded disc in it, and he was laughing. It was the biggest herniation he had ever removed.
The chiro, BTW was a highly respected and recommended one that many of my friends raved about.