Hello there!
I think your main problem is that they seem to re-occur. I was diagnosed over a year ago with 'paroxismyl hemicrania' (not sure if that is spelt right!), also a type of cluster headache. I have been successful in obtaining a Class2 medical since I responded well to the medication and had been free from headaches for over 3 months, whilst obtaining this license, I also enquired about my ability to get a Class1 since my ultimate goal is to obtain an ATPL, and the CAA at Gatwick said that I would have to make an appointment to see their neurology expert for additional tests. I guess you would be in the same boat - the question is, will these tests trigger your debilitating headaches? Hopefully not - but you would have to take the chance.
GOOD LUCK - I wish you all the best!