Hiya Sarah,
Typical signs are:
Pulling on ear
Crying when head moves suddenly
Crying when laying down, but ok if upright (thats a fluid thing)
Temp
Discharge from ear (other than earwax....when you see it, you'll know!!)

With Benjamin, we only say the discharge...mainly because his bed is still elevated cause of the refluxy chucking, so he wasn't laying flat
After the Dr, he had a temp, and now floor time isn't the happiest of occasions.

The most noticable is the crying when laying down, thats the one we always noticed at childcare, then you check the temp and its slightly up, and the rest followed!!