Need advice

My 11 month old had never had eczema, but randomly has it on the top of his thighs and stomach/waist below his belly button. It's not a rash. I'm breastfeeding and there's nothing new introduced in our diets. the only thing we did differently was changing his diapers from 7th Generation to Babyganics for a couple of weeks. Can diapers cause eczema? Or do you think he's just randomly got a flare up of eczema? I know how to treat it, i'm just curious of your thoughts or similar experiences.