Red circular rash on my hand—what could it be?

Greetings everyone.

I noticed this on my left hand the night before last:
http://i47.tinypic.com/2dhsm6h.jpg
http://i47.tinypic.com/2hgtern.jpg
http://i47.tinypic.com/24gswn9.jpg
http://i47.tinypic.com/kaobbn.jpg
As far as I am aware, I haven't suffered any burns or sustained any injuries that would explain this sudden appearance. It is slightly itchy, though I am not scratching or touching it.

Does anyone have an idea what this might be?

Looks like dermatitis to me. Doesn't necessarily mean it is, though.
Get a referral and see a dermatologist.

Did she have any tiny blisters on her?

It’s probably just dyshidrosis. You can find a whole thread ovdje covering it.