I'm not a medical professional but I've wrenched my back (as in meds and laid up for days, not an aching/ twingeing back, which I have all the time due to fusions in my spine!).
The answer is: it depends. Did you see the doctor? You may need to and get her recommendation (and remember that she doesn't know YOUR body as well as you do--you can tell if you're in pain or feeling the burn).
If you didn't see the doctor, start slowly. Do the warm up. If that works, try the last weights you used. You should know immediately if "something's wrong." If it is, put the weights down carefully and see your doctor.
Feel better soon!