Based on your answers, some of the most likely causes of your back pain include
degenerative joint disease (also called osteoarthritis)
muscle spasm or strain
polymyalgia rheumatica (PMR)
fibromyalgia.
Even with this long list, there are still other possibilities.
While over-the-counter pain medicines, rest (balanced with activity) and a heating pad may be helpful, it is important that you see your doctor to evaluate these symptoms.