Don't know if it's common but some people don't react well to medication. Sometimes it's an inability to absorb them, sometimes it's just odd and nobody knows why. Some people need much larger doses than others and others need much smaller ones. Brains are weird. It's hard to believe that absolutely no med works, though -- there are an awful lot of pain medications out there and also many natural remedies that have been used over the centuries, though they are generally much weaker than medications. Some people such as those with fibromyalgia have a problem with their central pain controls. Again, life is just odd. But has she really tried everything? I mean, off the top of my head, I can think of the following used for pain: neurontin and lyrica for nerve pain, aspirin, ibuprofen, acetaminophen, celebrex, vioxx, midol, dozens of different types of opiates both synthetic and derived from the poppy, marijuana, kava, willow bark, turmeric, ginger, benzos, nitrous oxide gas, ether, and that's just again not even thinking hard about it.
I doubt she has tried them all, I believe shes exxagerating, but i believe that she has tried so many different kinds, I've asked her every technical question about it, I just wonder if there is anything seriously wrong with this.