The breath test checks for bacterial overgrowth, but don't think it's a widely available test...not one of the "gold standards," anyway. You ingest a sugar solution (lactulose); if there's bacterial overgrowth, the bacteria will ferment the sugar into hydrogen and methane. You'll expel it through your lungs and they'll check to see if you are expelling excess hydrogen and methane. If you just went through a round of antibiotics, however, the chances of this being the culprit are slimmer.
The upper abdominal pain could be caused by so many things. How do you describe the pain? Burny, achy, crampy? How often do you experience it? During the day or during the night?
CathyA, I get a similar pain, if not the same. I would firstly suggest getting an ultra sound to check your gall bladder and check for gall stones. I also had to have blood taken to check my kidneys and liver were ok. All came back clear, but you feel better knowing that.
After lots of research i came to the clonclusion it is blockages in the colon. As you probably know, IBS used to be called Spastic Colon, coz in many of us the colon does not work exactly right. A normal person will have a smooth flowing colon ripple, and we can get very erratic spasms and cramps. During these spasms and cramps etc, contents of the colon can be shot forward or pushed back and fluid can be increased or decreased and you can get a blockage, just some contents get stuck and it can be very painful indeed. I get blockages in the bend at the top right on regular occasion. The bends in the colon are a common place for these blockages, but it can occur at any point within the colon. I also find that D can increase during these times. I deal with it by taking pain killers. It is the only thing i have found that works, but not all the time. High fat foods make it much worse, too, eggs especially, but that's just me.
I really hope this helps, but please get checked as i am not a doctor.