It depends what the nature of your back soreness is, which you fail to state.
If it's sore from working out, then, you need to apply heat to increase circulation, and do re-hab by finding your weak spots, making them stronger, and making sure your exercise form is proper. Folks with strong backs don't get backaches unless they have congenital problems or bad form. High reps in the effected area will also promote that circulation. E.g., if my legs are real sore I'll ride a bike or do 50's or even 100s to get blood flow into the area to get rid of the soreness.
If it's sore from a sprain, then, you'll want to get the inflammation down via NSAIDS and ice.
When in doubt:
R - Rest
I - Ice
C - Compression
E - Elevation
Back problems come from a lot of sources: imbalance, congenital, bad form, too much weight, being overweight, etc.
If you coddle a part, it only grow weaker. If you challenge it, it grows stronger.