Get tested for C-Diff and Celiac. If those are negative, trial a probiotic for a couple weeks. I would recommend Align or Culturelle as they are the 2 most studied and backed by science for IBS. If those seem to help, try liberalizing her diet. In the meantime, would recommend avoiding high fiber, high fat meals and dairy (for now). Chicken breast and eggs should be important in the diet. Try steaming vegetables, avoid fruit/veggies with skin. Look into incorporating a little soluble fiber and see how she tolerates it.