Has she been tested for celiac disease or other food related problems?

If your water changed recently she may be reacting to it. I moved one time to an area that had high iron which for me gives me diarrhea. I finally took petol bismal three times a day for a week to ten days and it stopped. I have had this happen for a few other reasons and I get diarrhea easily but the petol bismal will bring me back to normal. It sounds strange but maybe it will help and is easy.

@charlie5678 I can totally sympathize with your wife. I have pretty much the same problem. First I thought it was caused by the immunosuppressants that I must take, but I have come to realize that it is set off by certain foods, and I am still trying to figure that out. Since the start of it did coincide with my taking immunosuppressants I think they have caused me to be more sensitive to certain foods. It seems as if dairy may be the biggest culprit but lactose intolerance generally happens quickly after ingesting food with lactose, and with me, it happens hours later or the next day. I was having salads every day for lunch with greens, chicken, crumbled goat cheese and strawberries so I figured it had to be something in there, but for some reason, I didn't consider the cheese for a while. Has your wife tried tracking what she eats and cutting things out, to see if that helps?

Tomorrow I have an appointment with my PCP and I plan to speak to him about it. I will let you know what he says. It almost certainly is a food intolerance, or possibly IBS.
JK