Constipation can also be the result of certain food intolerances, most commonly dairy and citrus. I suffered terribly and painfully as a child when my mother went through a major health food phase involving oranges and grapefruit. Another constipation culprit is chocolate.
And although coeliac disease, ( intolerance of gluten), usually causes diarrhoea, in some people it produces constipation because of the damaged digestive processes, ( water uptake is disturbed).
And as D W a mom mentioned, smelly bowels could well be a sign of adverse reaction to a food, a sign of something causing the constipation. Lots of fibre won't solve this problem, and may even make it worse, because won't help "bind"/soak up the irritant-food.
Try cutting out dairy, chocolate and citrus and you may immediately see an improvement.
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