Falling?

For several weeks now, if not a month, I've been afraid of falling. Not emotionally. Physically. I can't step down off a snowy curb, without feeling that I'll lose my footing. The bookstore has two large escalators. I can go up, but down scares me. I just stand there watching all the steps go down without me. I feel I will fall if I step on. Even regular steps like in a parking garage, I have to hold the handrail or risk feeling I'll take a misstep. This doesn't happen all the time and it doesn't happen everywhere. I keep thinking its my new shoes and the slippery ground this winter. I will walk the long way around a snowy mound rather than walk through it like my kids will. And yes, there have been a few near-misses where I've almost fallen. Is it my fear doing that, or are they true near-falls? That is to say, is this all in my mind or is something else at play that I'm not aware of? I feel like its a mental thing, hence why I'm posting it here.