I was just reading in an Appalchian cookbook that excessive consumption of walnuts can have a laxative effect. I don't know how much "excessive" is, but one old timer recounting his childhood and walnut season certainly ate enough of them to notice.
You may want to search and see if you can find walnut oil. The oil is supposed to be what works on the bowels and you might can find it in a health food or fancy grocery store. Probably will be more expensive than aloe vera juice/pills and prune juice, but if neither of those have helped, it's another option.