Answer:

This could be a mild irritation from the swimming pool or duration in the swimming pool, particularly if there is high level of combined chlorine (used up chlorine) and not enough free chlorine or if the pH is significantly high or low. Or was she wearing nail polish or any nail accessories? Could be a reaction between the chemicals in the water and the substance on the nails. There are also a number of non-swimming pool related causes for such a reaction.