What Causes Dizziness Along With Weakness In The Legs?

I started experiencing some dizziness, fog, leg weakness about 6 weeks ago. I do have hashimotos, but this has never been an issue before. I am extremely active and run, exercise 6 days a week, I m slender and eat well. I would quite readily run on the treadmill for an hour but feel that I now need to hold on with one hand or risk falling over, which, I have never done. I had my eyes tested and I do now need distance glasses. I do experience anxiety but up to this point have recognized panic attack onset. This is very different. The only thing I can attribute this to is that my son, without warning, and after the fact, told me he had moved to China. I was terribly upset but masked it for his benefit.