Hello Boxin,
I have a brain cyst so I am familiar with the issues your husband is facing. Clear fluid draining from ears or nose is one of the symptoms my doctors are always telling me are important. The clear fluid _could_ be something as simple as an infection that is clearing out, but it _might_ be something seriuos.
It all depends on where his injury ocurred and whether there was any damage to the skull around his ear.
The only way to know for sure is to have a doctor look in there. My suggestion is that you call your doctor right away, of if there is an emergency room nearby call them on the phone and ask them.
Mike
Moderator, SR