I have had a weird pain in my back for the past three weeks. It's right-sided (near the spine) and very vague until I press on or near the spine in that area (the top of my waist in the back - possibly t12?). It's usually sore when I wake up, but stretches and naproxen sometimes help. I have been relatively inactive lately (no gym in months, lots of computer work) after years of regular exercise.

Is this likely muscle-related? If so, which muscle(s) should I be stretching and working on?

I'm only concerned about it since I leave for europe in a few days and will be gone for several months.

Thanks for any suggestions!