Back pain can have so many causes. It's difficult to say what yours is from. Yes, it could be from the epidural. This could be a temporary side effect, or it could have longer lasting consequences. If it continues after a few weeks, I would get it checked out.
I always get backache after my c-sections. Mostly it's from the readjusting of not having the baby weight in my stomach anymore, so my posture is thrown off. I also don't sit in a good position with breastfeeding due to the fact that baby can't "lay" on my stomach in the beginning.
After this c-section, I also got bad lower backache until I realised I got a UTI! It travelled to my kidneypipes, which caused the backache. After a course of antibiotics, the pain went away.
What helps me loads when I have backache, is to put a hot water bottle or heatpack on it wherever I'm sitting. Good luck!