Why does my lower back hurt after a kettle bell workout?

I recently hurt my lower back after a kettlebell workout. I used the proper technique and form such as tightening my abs and buttocks during lifts but, I still became hurt. My lower back started off being sore after a kettlebell workout which I thought was because I’m a beginner but, it became painful the following day. I’m asking any Kettlebell practioner to what is the problem. Is kettlebell for everyone or only for a certain few. Like I stated in the beginning, I used the proper form and technique that I have learned from Steve Cotter’s videos on kettlebell. Really need help. I’d appreciate if someone who’s familiar with kettlebell workout to respond. Thanks.