Lower back pain can actually mimic a number of other diseases some of which need to be treated quite quickly.
For instance pain stemming from a kidney infection is in the low back but the kidney's lie either side of the spine just above the hips, which is so similar to low back pain.
Kidney pain is felt as a tenderness in this area. The problem is that the pain of the kidney infection is tricky as it can also radiate to many different parts of the body. However it is quite common to also include pain with urination and fever and chills.
Some other diseases that can mimic back pain are Arthritis of the spine, Osteomyelitis an infection of the bone but more common in children and diabetics. Lupus and Fibromyalgia which are immunologic disorders as well as Cancer, Shingles, Rickets, PMS, Polymyalgia Rheumatica or a urinary tract infection and many more.
So, the best thing to remember is to never leave a strange pain for long before you go and see your GP as with some of the conditions listed above the earlier the treatment the better.