Hi, worried mother,
Wow. I sympathize with you. One of my granddaughters had her first Migraine at 2-1/2. It's horrid.
The questions you're asking are really going to have to be investigated by doctors because they're not ones that anyone can answer via the internet, but I'll try to give you some information you can discuss with the doctors.
The first episodes you describe -- sharp pain and vomiting -- may have been Migraines. Again, only a doctor can confirm that diagnosis. That' can be difficult because diagnosing Migraine is done by reviewing the patient and family medical history, studying the symptoms, examining the child, and ruling out other causes for the symptoms. It's going to be important for the doctors to know if there's any history of Migraine in your family or her father's because Migraine tends to be hereditary.
With the seizure being months after the other eipsode, it's very difficult to say if the two are related or not.
Your best course of action at this point will be to find a good pediatric neurologist.
If you'd like to talk with other Migraineurs and partent to get some additional information and support, come join our discussion forum. You'll need to register again once there because it's a separate membership database, but you can use the same member name, email address, and password that you used here. You can find our forum at http://forums.healthcentral.com/discussion/migraine/forums.
Wish I could tell you something more solid, but I simply can't.
Please keep in touch, and let me know how things are going?
Good luck,
Teri