My doc always checks my under my rib cage(he has me breathe in while he pushes gently under and in an upward motion)
There is a ...what is the name of it....it's thin and it is under your lungs....
Anyway I think, opinion only, that when you are bloated or inflammed it pushes up on this(the thin flimsy thing that it's name has escaped me)
I would guess maybe that is what it is.
If it bothers you I'd call your doc and talk to the nurse.
Sorry for the brain fart...they happen more and more with three kids...lol