Burning sensation

Ok so i am in my third trimester at about 30 weeks and i have been having a burning sensation on my upper right part of my belly. Feels like i am on fire. And hurts when touched. What the heck is going on and ehat can i do to make this pain go away?? Ive been dealing with this off and on for weeks now. It seems to get worse when sitting for too long or laying in certain positions too long. Any advice will help.. Thanks