Sorry for missing your post, NytViolet! I can relate entirely, and I'm glad my experience helped to reassure you. I agree, that if your pain had a sinister cause, it should've become more severe by now.
This year I've learned a lot about my body, mainly the fact that I can't treat it as badly as I used to when I was younger (I'm in my late 30s). My body punishes me now for things like poor posture, not enough sleep, and so on. My entire 2014 year has been full of unexpected new symptoms, and all have had innocent, and most likely age-related, causes so far.
I've had pain in and around my ribs for two reasons this year: bad posture (leaning too much on the arm of my couch), and a sudden change in my diet (I ate broccoli, cabbage, brussel sprouts, kale, etc. two or three times a day, causing extra gas which gave me pain and pressure in my upper abdomen by my ribs).
So I would recommend taking a look at lifestyle habits that might not have caused your pain in years past, which might be causing them now. Something as simple as sitting in a different chair or getting extra support for sitting or sleeping or whatever, might relieve your symptoms after a little while. And who knows, changing your diet might also help, as it did for me when I quit those veggies for a couple weeks. You never know.
Of course, always see a doctor, just to be sure. But in the meantime, making small changes at home or in your diet might be just what you need. :)