Hello girls. Experienced moms, please help me, what could it be? Just …

Hello girls. Experienced moms, please help me, what could it be? Just one spot, not raised, dry. Not like a bite, not like an allergy, completely on IV, for the last 10 days from clothes, food, hygiene products nothing new tried that might have been an allergen. If anyone had something like this, please tell me what it could be?