I have constant back pain. Sometimes with pain shooting down my legs or across to hip bones. This could be nerve impingement (sciatic or other nerve) so since it came on suddenly for you I would see a doc.
I have heard that low back pain is one of the most frequent symptoms of fibro but don't quote me! I am not a doc!
Fibromyalgia, TMJ dysfunction, Myofascial Pain Dysfunction, Chronic Fatigue Syndrome, hypothyroid, bruxism, endometriosis, medically induced menopause (everything removed!), major depression, going through a divorce to top it off!
Ultram, Soma, Ativan, Lyrica (on and off), Armour Thyroid, Famvir, can't tolerate SSRIs or NSRIs.