Nela, Sorry to hear about all of the pain you are in. I also have lost about 25lbs maybe even more. If all of your G.I. tests have come back normal then maybe you should go to a gynecologist and see of you might have endometriosis. I have it and I also have alot of back pain with it. It's possible you have that and the IBS. Is the pain constant or can you pinpoint it to a certain time of the month. Even with endo, I get pain sometimes all month long and the really bad back pain more towards the end of my period.Good luck. LOU026