Can only sympathise because I've been through that. Unbearable pain. Loads of clove oil helped as did a hot water bottle on my face. The antibiotics should kick in withing 36 hours at most.
Thanks all. Booze would be my preferred painkiller, especially a rather large Manhattan. Unfortunately, drinking with Metronizadole has a better than average chance of inducing vomiting. I have to wait 48 hours after course before I can imbibe, so that's next Sunday :(