Where's the pain and what does it feel like?
Is it short, sharp pain or dull ache when moving about. If it is the latter and in the lower back then it'll just be muscle soreness 99/100. I get it all the time after deadlifting, I'm lifting over my body weight now and the soreness is just as bad as when i was only lifting light. It'll take a while for your body to adjust to deadlifts but keep at them cos they are second to none.
Just ensure your form is spot on, get someone to check for you whilst your doing them. It's the easiest exercise to injury yourself doing and can cause long term problems if not done correctly.