as one who's had a few back injuries from deadlifts
(see sig) here's my take:
if it's really painful, then see your physician.
by "really painful," i mean, for ex., you can't turn over in bed without
it hurting like heck, it hurts to inhale, you have to take days off from work/school, etc.
the physician may prescribe some muscle relaxants and pain relievers
and possibly cortisone shots. subsequently, you won't want to lift
for at least 2-4 weeks.
if this doesn't do the trick, then you have to do physical therapy.
for lesser pain, try various physical therapy-type stretching exercises
2x per day and your choice of pain reliever. for me, this ALWAYS cures minor
back injuries that don't require a physician's help within 1-2 weeks.
if it's not painful, then you're probably ok.
i can have some serious soreness for up to 4-5 days after
a heavy workout, but i'm fine after that.
make sure your form is right.
you may need to deadlift less frequently.
some people make best progress by doing deadlifts every 7-10 days.
