I have had migraines of various types since age 16 (33 years!!) & no sign of epilepsy & there is some in my family, & aside from normal stress or pain related brain hassles (at the time not constantly etc) no brain or iq issues. So I find the whole idea bizarre that migraines would cause iq loss - think how many people suffer them & how often have you heard anything this weird mentioned. I am calling the drs idiots not you!!!!
Many epileptics hold down demanding jobs so again I find such a conclusion/explanation bizarre.
I have experienced (personally & several family members) specialists misdiagnosing health problems though - including making a diagnosis when they didn't know the answer!!
suggestions:
1. Have you obtained several opinions (without dr each talking to the other!!)??
2. Have you been to see what alternative therapists say - homeopath, naturopath to start (actually pm drvenugopal a homeopath from india who posts here - he might be able to give you some ideas/leads)??
3. Go to google & type in migraines & brain damage also treatment of migraine related brain damage & (to my amazement - it does exist) you may find some help - but given your situation i'd suggest getting a family member/friend to do this as there's alot to plough through!!
4. Look into natural supplements that help memory/brain function gingko, also smart nutrition.Com has some tablets that might help & i'm sure there are other on-line places to get help/meds etc.
5. Go to dynamind.Com or alpha-stim.Com & rent/hire a ces machine (cost to buy about $us200)- this machine has done wonders for my migraines - they help the brain in lots of ways & from what you describe - i'd be getting all the help I could!!