I would definitely pursue allergy (sensitivity) to milk in mom's diet.
Mygrandson had same thing plus occasional bloody stools and when she could
definitely link worst episodes to times she had dairy.  I think if she had
been able to eliminate it completely she would have completely solved it.
Since then I have found that I have dairy sensitivity and have cleared up some
problems I've had for years that I thought were "just normal for me" and I
remember that she ahd similar problems when she was a baby and I used a lot of
dairy.  She ahs found that she has also helped some of her problems (adult
acne one of them) by almost eliminating dairy now too.

Linda Mosher. Kalamazoo, MI LLLeader