My baby’s face smells like fish!

So lately I’ve noticed my little ones face or head smells fishy, I just assumed it’s the milk that drips behind her ears and into her neck rolls when she eats that’s going sour hence the bad odour. But I gave her a bath today and made sure to wash everywhere and her face still smells fishy. It’s so gross. I’m not sure what it could be. Has anyone else every experienced this?