i have the same exact feeling ALOT. especially if im not sitting completely upright for a while. i asked my Dr, she said its a common pain for pregnant woman and for some reason, especially on the right side. she said its just from feet kicking and everything being pushed up into that area. but its right under my right breast, on the curve of my ribs and the only way i feel better is to sit on couch with a pillow behind my middle back, pushing my breasts outwards. unfortunately, the Dr said itll maybe get worse as baby gets bigger (im 33 wks and 4 days) but will go away after pregnancy.
It could be gas maybe hot sprite or hot tea.