Cyst found on my 6 year olds peneal gland

hi I was wondering if anyone could help? For the past year my son has been suffering with headaches, about six months ago out of the blue he started screaming in pain (very unlike him) within minuets he was screaming the light was hurting his eyes and his head was going to "explode" he then what I could one describe as a very short fit (30 seconds) and then his whole body went limp, he was violently sick. I called an ambulance but within an hour he was back to his normal self since this episode his constantly complaining of a headache and has 1-3 of the above episodes a month each time going from bring fine to extream in minuits. Early September he was sent for an MRI I was called in on Thursday where I was informed he had a cyst on his pineal gland. The consultant has said that they are not known to cause this kind of reaction. He has been refered to Great ormond street hospital. Has anyone had any experience with this could you please tell me what the plan of action is likely to be as I'm worried sick and hate watching my baby in so much pain. Also I don't know if related but it all ways happens in the evening or during the night when his sleeping.