It seems an inevitable part of the human experience to have low back pain at some point. There is tremendous mechanical strain in the area where the lower lumbar spine curves and meets the sacrum. The thick strong muscles that hold us up all day can strain under fatigue or poor mechanics while sleeping or lifting or other less easily explained phenomena. That kind of back pain is what is most commonly referred to as having put your back out. This is a deep, strong muscle spasm that can be debilitating, causing pain across tha lower back. This kind of issue is relieved with heat, stretching, anti-inflammatory medicines, like ibuprofen or naproxen. (Motrin or Aleve.) Ice is a great anti-inflammatory and heat is an excellent muscle relaxer. Heat and cold do different things for us, not opposite. Do whichever one feels better for you. If you want to use both, apply heat, (never sleep with a heating pad on), then stretch while the muscles are all hot and flexible. Then apply ice. Heat. Stretch. Ice. Heat. Stretch. Ice. Sometimes it can be so serious as to require prescription medicines like muscle relaxers and pain relievers.
If your back pain radiates down the buttock and even down the thigh, that may be indicative of a problem in the disc between vertebrae pushing against the spinal nerves. This is often referred to as a slipped disc, bulging or ruptured disc. Don't panic. One common phenomenon is called sciatica. This is caused by the sciatic nerve being compressed as it exits the spinal column. It is a shooting burning pain down one buttock, the back of the thigh, then the side of the calf and finally all the way to the big toe. This can and should be treated conservatively with stretching and medications, too.
There are situations that are emergencies. Problems with bowel and bladder control or numbness and weakness in a leg should be considered an emergency. That type of symptom would require immediate consideration of a more thorough investigation and the possibility of surgery to get that nerve freed from pressure. Statistically speaking, people who have had back surgery can get symptom relief sooner than people who take a less invasive approach, but within ten years, both groups end up the same.
Seek evaluation and advice from your health care provider as you see appropriate. If something isn't working for you, and only you know how you feel, re-evaluate. Be patient within reason. Be persistent in your self-care as well as seeking professional care when you need it. Massage, osteopathy, acupncture, energy work, chiropractic and yoga , as well as other modalities can all help. Figure out what works for you. Stay fit. Rest well. Prevention is much easier than treatment.