funny smell.

I have two daughters. I bathe them daily and put new panties on them every morning and every night after their bath. my oldest daughter is fine, but my youngest daughter always seems to have this... smell. it almost reminds me of the smell I have after spending like its in the sun and then working out lol like sweat mostly. but a tiny bit fishy because it's coming from down there. she doesn't have a rash, and does really well with wiping herself. nothing seems to be wrong with her, no discharge or anything. It's just this smell. I was wondering if you ladies had any advice or have dealt with this before? and if it might be something I need to go to her doctor about I don't even know how to explain it? it's kind of a weird topic for me. Any kind words of advice or support are appreciated. thanks in advance