I have this on and off. I have psoriasis. It's def not to do with me not drying behind my ears, because I'm a bit obsessive. Occurrence is random. It is painful. The fluid is the white cells coming out of the wound to protect it.
It would be hard with a littlie to stop them scratching, but that's really the only thing I find helps along with a good dose of steroid cream....but mine is pretty bad.