Depends on the where the back ache is. I have chronic pain in my back due to a varity of reasons. I find that my back problems became worse because I held myself a certain way and stopped using my back which made it less flexible. My goal right now is to get more flexible to try and decrease further problems but you have to be careful not to push it too far. I do take anti-inflammatories with built in stomach protection and use a range of hot/cold compress when its at its worse but it really does depend on where your pain is and how acute it is at the moment. I found cranio-sacral therapy good and also physio to start of the movement again so that I could then continue to work in the stretches. Posture is also important. My back has numerous problems though some probably from no addressing the problems at the start. Add some more detail and the advice you'll get back will be more specific. Hope it improves for you.
Heating pads, warm baths, Ibuprofen, exercise. Where is the pain located on your back?