What Causes Loose Stools And Indigestion In A Child?

My daughter is 17 months and for the last three weeks or so has had loose stools with an increase in undigested food, mostly vegetables, in it. Her stools have somewhat more odor and are paler in color than usual. Recently I noted some mucous in her stools. She does not consume an excess of milk. We have not traveled lately or been around water that could be contaminated. We do have two indoor/outdoor cats that she is crazy about that I do have to treat for tape worms on occasion. I have not seen any evidence in her stools of worms