ok, im going to ask TMI questions, so you dont have to answer them on here...but just think about them. what are your bowels like? are you regular? and do you pass wind regularly??
the sholder pain, is it in the tip of your shoulder? shoulder tip pain is reflective of pressure on your diaphram, which is mostly caused by increasing pressure in you tummy, in extreme cases like blood etc (but for people who have recently had surgery and stuff), but can also be caused by extreme wind.
in saying that, if it is gall stones get checked out, get checked out anyway, because maybe something like changing diet etc might do wonders.
hope it eases for you soon!