can someone tell me how this happens?

Yesterday, as I was getting ready to sit down and edit some more photos, 

I lift up my foot and see this.

It's not a bruise. It's a stain of some sort.

There is nothing squashed on the floor anywhere, and I don't have any berries in the house even. Nothing squashed out on the patio either.

Nothing squashed inside the shoes i was wearing.

I showered yesterday and the day before.

It a mysterious purple blotch on my foot.

I scrubbed it last night and it faded, but it's not gone.

Where in the hell did it come from???