Hmm, sounds like something is going on. Have you had a CAT scan or MRI of the brain? I am a retired nurse. I had difficulties. I passed out on my lunch hour at work at the hospital a few years back. I was admitted to the hospital the same day, a lot of tests were performed, but nothing was found. I was then ok for a while. Then I was seeing a neurologist, and he ordered an MRI of my head. He called me the same day I had the exam. He told me there was something there that needed to be checked. I went to an oncologist and had a laser on the mass. I was okay, but when I had another MRI, the mass had returned. I went to another oncologist, and we decided chemotherapy was my best bet. He did a heavy dose of chemo. I have been cancer-free for 6-plus years - as of now. Just keep checking and see other doctors, something should show up. Good luck, my friend.