JuicyO, DS2 suffers from migraines - he gets flashing lights and then the headache. He usually has a couple of hours when he knows he's going to get one, then 4 hours or so with the headache, then a few hours of feeling a bit rubbish. He has had them in clusters though, where he's had a new migraine every day for three days or so. He used to take both paracetamol and ibuprofen at the first sign of the aura, but now he has sumatriptan from the GP which he takes. This doesn't stop them but makes it possible to do something other than lie in a dark room feeling sick.
I think if your DD keeps having headaches as bad as that she should see a GP, but it's possible if she has a few early nights she may feel ok again. We don't really know what DS's triggers are but we think lack of sleep, loud noise (eg gigs without earplugs) and deydration all play a part.
Hope your DD feels better soon.