I know how much it sucks to watch your little one in pain. I don't have any knowledge of herbs or anything, I always ask myself, what would my grandmother have done before OTC meds were ever-present? Cool baths, washcloth to the forehead, let the little one hang out in just a diaper, sips of ice water, open a window or turn on the A/C even.
I wish both a speedy recovery!
PS My little one (now 3) has never had a fever that lasted more than a day, so you probably won't have to worry about this for long!