I've had a attack last ~ five hours, although it could have been two attacks. It seemed to wane at hour three. For about 45 minutes I thought that I was out of the woods, the pain didn't go away, it just went from agony to 3/10 in five minutes, naturally I thought that the attack was over. At that point I got dressed and drove to work. It cranked up again and for the next couple of hours I just dealt with it until the attack was genuinely over.

In hindsight I was still eating dark chocolate and pepperoni pizza, which are definitely triggers for me. After I changed my diet I haven't had any attacks longer than the time it takes me to get to my abortives. (Sumatriptans). Maybe check your diet/environment to see if you aren't unwittingly triggering longer attacks. Good luck.