Although I am C and not D, I think the same principle applies...how fast did you increase dosage? If you increase fiber too quickly, you will have gas and bloating...same if you are taking too much. I always had some gas and bloating when I increased dosages, but it went away in a few days time. If it doesn't go away, try lowering your dose a bit.
Also, as wonderful as Acacia is to me and many others, sometimes folks find that they have to try another fiber all together to get rid of side effects. For me, Acacia is a godsend! I hope you don't get discouraged and can find a dose that is comfortable to your body!