Sez, can you describe the pain? All the discomforts I've had associated in that area have been either the baby sitting in a nasty spot, indigestion, or heart burn. Is it affecting your breathing at all? Have you tried adjusting your position?
I hope it goes away soon for you. If you are concerned, do give the hospital you're booked into a quick buzz and speak to one of the mids. Or you could try nurse-on-call.

HTH

MG