I feel your pain, I suffer from terrible migraines - fortunately they stopped in pregnancy. I've had one since DS was born (he's 4 weeks on weds). The doctor gave me some codeine a few days before for severe neck pain, it says not to take when bf on the packet but doc said a short course would be ok. The codeine seemed to help with the migraine though.
When not pregnant or bf I have sumatraptin on prescription - it works within an hour or two, it's brilliant, but you can't take it while bf - however you can take it if you then don't bf for 12 hours afterwards so if you've got a decent stash of expressed milk and are getting desperate for pain relief this could be an option.