Hi,my mother who is 54 now has had thease bad dizzy spells ,"as she calls them".she has had every darn test you can think of,blood work done and still nothing is found.the other day as she was driving on the highway she got one of the dizzy spells and had to pull over,it did not pass so she had to call my dad and brother to come and get her off the highway as she could not see from it to drive home.she has had a slight stroke a few years ago and ever since then she has had very bad headaches,she is a diabetic,she is on medicationas for that.back in May 2006 as she was walking outside to put some stuff in her truck she got a dizzy spell and she fell and hit her poor head on her truck ,had to go to the ER and get a few stitches above her right eye brow.she keeps a headache every single day and she says its just in one spot of her head that she egts thease really bad headaches at,its on the right side of her head in the back and she says it feels like someone is pulling her hair as hard as they can in that one spot,again more test and blood work and nothing,im very worried about this because i know there has to be something the drs are missing or are not even looking for,im scarred that it could be a tumor and its not showing up as one,and one day she will get thease dizzy spells and either be driving while this happens again and cannot get over off the road/highway and get into a bad wreck or she will fall and break something like a hip.can you tell me what this could possible be or give me some kind of idea on how to go about helping her,i might add that when she has thease spells then she is home in bed for 2-3 days after and does not feel good

Optional Information:
Female , Age: 54

Already Tried:
dr visits,blood work done,tests done like CT MRI,etc.