I had one that about a year or so ago, hurt her foot real bad, and acted the same way,would not move it, kept it tucked, was just sitting there for probably 2 days before she finally started to move / limp / flop around again. Something fall on her foot, crush it, it get caught under something. You say there is nothing for them to get hurt on,but all it takes is them to somehow get it under a door jamb or around a corner or something stupid that on first look, it's a no brainer that 'it's safe', they get it caught pull it real hard and pop, break, sprain, fracture, whatever.
That leg where she has her toes curled in, if I was a betting man, id say is probably the foot she hurt. Try to check for scuffs, or anything obvious BUT if she's really adamant about not letting you touch her, then don't. If it's not bleeding then I don't think it's too critical at the moment.
please keep us updated.
Aaron