Call your doctor and ask if he/she will call in just enough pills to get you to your delivery date.
W/D is certainly no fun, and Effexor is notorious for having a rough one. I would encourage you to make sure you aren't cutting it close with your shipments. Pay close attention to how much you have, and order your refill in enough time to receive it without running out.
The good news is, once you restart the Effexor, you should be feeling better pretty quickly, probably within a day or so.
Take care!
I just started Effexor myself a couple of days ago. Call whom ever you get your meds from and ask them to rush the order. In the meanwhile hang in there. Call your doctor if it gets really really bad. You could just have the flu. Good luck.