M.M.
The basic sitting position with your arms on a desk can cause what you're describing by itself.
Also, if you're carrying kids around, carrying them requires you to hold them in a hunched over position (whether you notice or not), which puts strain on the lats and upper vertebrae. If you have large breasts, that "helps" too, causing that hunched over position.
And finally, weak core just hammers it all home (this is not a suggestion about your fitness level, rather a common problem).
In short, get thee to a chiropractor that also has a masseuse.
A good chiropractor will explain to you exactly how your condition arrived, and what steps you can take to correct it on your own.
Pain killers and massage alone will not solve the problem, just mask it. You need to learn how the body interconnects, and learn what stretches, strengthening exercises and habits you can adjust to feel better.
I LOVE my chiropractor. He's taught me so much.
Do some research and find a good one.
You'll never look back!