Dont know wether I can be of any help, but I have Hemeplegic migraine too. I had all the tests you had but wasnt offered any treatment, but that was because of other problems, there definitely is treatment you can have.I have used alternative methods they have helped. It does get less scarey as time goes on, so dont give up. Get in touch any time you want cause I know how fed up it can make you.
Thinking of you Moth
PS Dont know wether you have had any blood tests but it is worth having some because there is a condition that makes you have either extra platelets or extra sticky platelets that can make con dition worse.