Before you go down the food allergy root, this ear stuff couldn't be more straightforward. Kids ear infections and threats of grommet is real bread and butter daily homoepathic treatment for the average practitioner. Grommets are fine for keeping the problem at bay for a while and sometimes it does so for long enough for the child to grow out of it, but they don't deal with the underlying problem and they can fall out and you've not dealt with the cause of it.

Go and see a good homoepath. Apart from giving therapeutic remedies which may help in the short term, the right course of treatment - probably constitutional remedy, followed by miasmatic remedy to deal with underlying tendency, constitutional again et etc etc will take care of it within a few weeks even there is an allergy problem. If the body is in better health, any allergy can disappear along with other problems when the body is strong enough to throw it all off.