Sprained!

I went to the doctor on Tuesday to find out why my left foot was swollen and hurt so much. Turns out it's sprained. I have no explanation for this. I've done no twisting, no falling. Doc thinks it might be a combo of overwalking, the orthotics in my shoes, or the stretches I do for my back. (and before you ask, the stretches involve alot of leg and foot stretching)
So, I took 2 days off work but I returned today. I'll just have to take it easy. I'm wearing a brace that helps a bit. When I'm home I'll just have to keep it up and ice it. (fun in the winter)
Last month I had shingles. Now this. I'd ask, "What's next?" but I don't want to know.