Mouthing soaps, lotions, haldi or other non-edibles is usually oro-sensory seeking or pica, not primarily a gut problem. Two useful first steps: (1) basic blood investigations for iron and zinc deficiency — pica is sometimes linked to these and is correctable; (2) an occupational therapy assessment for oral sensory needs. Gut testing may have a role in specific cases, but do it on a doctor’s or qualified nutritionist’s advice rather than as a default. Meanwhile, safe oral-sensory alternatives (chew tubes, crunchy foods, gum massage) reduce the behaviour for many children.
Disclaimer: This is general information shared for parent awareness, not medical advice. Every child is different — please confirm decisions with your child's doctor or a qualified, RCI-registered professional.