My chronic back pain lasts around 2 months after I do something (physical) to reignite it.
The Paracetamol/Ibuprofen tablet works for me, however I never take more than 1 per day... and definitely not every day as I am now on blood thinners.. read the warnings.
Also a back massage is good for temp. relief using an anti inflammatory gel. I find heat pads don't really help me and really smell, especially the Thai Tiger Balm ones.