Hello and welcome to HCM I understand your worry about vitiligo. We ned to think of more common causes in kids first. If he has a history of allergies or eczema , it could be a condition called pityriasis alba, which is harmless and generally resolves on its own. Sometimes it may also be associated with vitamin deficiencies. Another thing you have mentioned is the toothpaste. It has strong chemical salts and can definitely cause scarring and chemical reactions in the skin. It can also cause something similar to vitiligo called chemical leukoderma, which seems highly possible. Please make sure to find a way to stop this habit as it seems like the cause. You can start treatment as advised. Apply a very mild steroid cream like desonide cream once a day for maximum of two weeks,maybe during sleep, and an aloe vera based cream or lip balm at other times. Give a multivitamin syrup supplement daily. Try and get sun exposure for 15-20 minutes daily. Watch for improvement, and consult with a dermatologist regarding confirming the diagnosis and further treatment. Colour will take a while to get back to normal, so regular follow up is required. Hope this helps you.