My sister has been complaining for a few days now that she is having very strong, stabbing-like pain on the right side of her ribcage. She also has Type I diabetes, and we both want to know does that affects the pain. The pain gets worse when she is breathing, so it seems like she has either cracked rib (this one is very unlikely) or she has pleurisy, or some other kind of inflammation or infection. It hurts her more when she is sitting and in the morning – if that info helps. Are there any other causes for pinpoint pain under rib cage? And does diabetes affects this in any way?
my dad recently experienced something similar - he couldn't breathe in fully because each time he did, a sharp stabbing pain would shoot down his right side. It's almost identical to what your sister was complaining about: it was worst in the morning and there was no way it was caused by a cracked rib.
So, if it'll help you at least a bit, dad had an x-ray done and there were no problems with his bones nor did anything show up as problematic on his lungs. I don't know how much difference does it make that your sister is diabetic, but all my dad got for this condition were NSAID painkillers (ibuprofen),
Wish you all the best,