Once good way to do this is to put crushed ice and a little water in a plastic bag, seal it well, cover it with a towel and apply it to the affected area.
A bag of frozen peas or sweet corn kernels also works well for this, as do refrigerated towels.
To avoid damage to the skin and underlying tissues, apply the ice for not more than 15 to 20 minutes at a time, allowing 20 to 40 minutes between applications.
Three of four applications a day should be enough to offer relief.
Do not use cold applications if you are very sensitive to sold or if you have Raynaud's phenomenon, a disorder of the blood vessels in the fingers and toes that causes them to contract suddenly in response to cold or emotional stress.
Be very cautious also in using this treatment if you have rheumatoid arthritis.
Try not to doze off while an ice pack is in place.
It is very dangerous.
After using ice for about a 48 hour period, you may try an application of moist heat to relax tense muscles and ease stiffness.
Apply heat for 20 minutes about twice a day using warm, moist towels or take a warm shower or bath.
A bit of cautions when doing this, do not use heat if your back pain was caused by a blow to the back or by a fall or other accident.