Don't Know What is Wrong

The symptoms started over night. I came back from the Ukraine on a Friday night and Saturday I had these symptoms. Fatigue, my head feels like Im in a fog. I have a problem thinking of words sometimes. I have tingling in my fingers sometimes. I feel unsure in stepping or walking, not that I fall down or walk a crooked line, just if I'm lightheaded. I've had blood tests, MRI, CTs, EEGs(wires to my head), I've seen by a Nurologist, and everything came back clean. No shortness of breath.....

This started on 28 Jan 17.....

I can't figure what is wrong. I though I was poisoned in Ukraine because I was outside in the cold and we huddled near a potbelly stove in a closed garage to keep warm.

Any help would be appreciated.....