I have tried to compare it to having a horrible toothache, the stomach flu, and the feeling of being scared as if you just missed a severe car crash all at once. But that still doesn't seem to convey the information to some.
I think describing Migraine to someone who doesn't "get it" is one of the hardest things to do.
Teri Robert wrote a great friends and family letter, maybe that will help you, or give you some good info.
Remember, Migraine is a neurological disease, not just a "bad headache" like some think. Having a migraine attach is a flare up of this disease.
See this article: Migraine and Headache Education for those who "don't get it". There are some great referances in this article you can print out and give to your loved ones to help them understand.
Hope this helps a bit!!
Pain is a hard thing to describe. I usually say that when you get the onset of a migraine, you worry that you are going to die. As it progresses, you hope that you are going to die.
On the positive side, nothing beats the feeling of waking up and realising that the pain is gone. You're scared to move at first, in case it starts up again but finally you realise you are OK, pain free and appreciative of the world in ways the non migraine sufferer will never know.