Yorkiegirl, my son has just had his second set of grommets in, he's 6, so we've been through this many many times too. You have my sympathy.
One thing we found worked really well, through desperation more than anything, was a doze of piriton syrup. I think because it tends to dry up any mucus behind the nose, going into the ears etc and it makes them drowsy too.
Worth a try if you've got any around?