What Causes Sudden Confusion Followed By Dizziness And Nausea While Driving?

My husband experienced confusion while driving his car, could not determine how to pull it in the driveway and backed it up into another car not knowing what to do. He then experienced dizziness, a headache, felt warm, and nausea. The headached came after the confusion subsided. The confusion lasted less than 10 minutes. He was admitted to the hospital with the possible diagnosis of stroke or TIA. All tests were negative for any stroke or related problems, ct, mri, blood work, carotid ultrasound, echo cardiogram. His blood pressure was normal and his choesteral was under 200, the only number slighlty elevated were his triglycerides. He does not have a history of migraines. He was released and they said it may have been a acute confusional mirgraine but this was a diagnosis of exclusion because they could not difinitively tell if it was a TIA because all tests were negative. What is the difference between a TIA and a confusional migraine and are there any additional tests that can be done to determine more specifically if it was a TIA (or migraine).