If she isnt touching her skin perhaps it is just itchy? If she isnt touching the the bath that sounds like it may be the answer. I know my DD cant wait to grab and rub once the nappy comes off so much so it looks like she will her herself and she is only 9 months ( so much so I've given her nappy off time every day and it seems to help) so perhaps its just something as simple as its itching her and she needs to scratch and cant get at it? I have very sensitive skin and it seem so does my DD.

I would definatley take her to the dr, and also keep an eye out for any discharge or the white rash associated with thrush. If its on her nappies (if you use cloth) you will need to disinfect them all with canestean as she would be reinfecting herself.