Hi lovinlife,
I'm sorry your daughter is suffering so badly. I've been away or I would have posted sooner. I too suffered migraines as a child and they didn't have any of the medications they have today.
My mom found that a cold cloth on my head with Childrens Tylenol and Childrens Gravol worked. I still take the adult versions of these medications. Medications often don't work because your stomach can't digest anything. I have found that gravol settles my stomach and relaxes me so the tylenol can work. I do take stronger medications as well but I think it would be dangerous for a child to take anything else.
I take Topamax and I really recommend talking to a neurologist who has worked with children and Topamax. The side effects are really severe and I suspect they would be even worse in a child. I wonder if Topamax has been tested on children for migraines. There are more gentle anti-epileptic medications such as neurontin that don't have the negative side effects Topamax has. I know Topamax is the latest and greatest, but I don't think it has a history with children.
It sounds like you're on the right track with an allergic reaction to a medication or something else that has come into her life suddenly. When someone goes from no (or few migraines) to a constant one for weeks, that tells me something has changed - though I'm not a medical professional just an experienced migraine sufferer.
Your daughter mensioned her head was numb and you thought it might be swollen. After a really bad migraine my head may feel numb or bruised from the blood vessels expanding. Her forehead may be swollen from pressing on it or rubbing it from being so sore. Though it's still good to discuss / show the neurologist.
Good luck finding a solution and keep in touch.