planned parenthood is a place anyone can go to for birthcontrol or advice on sex type stuff or different examinations... and depending on the persons income it can be as cheap as free...
they have them all over the US
http://www.plannedparenthood.org/
plug in your zip code and theyll tell ya where the nearest is...
as for confidentiality... everything there is confidential... altho in this case they may be obligated to report the abuse...
but if she is worried about it being infected she definently needs to be checked out... surgical infections can be life threatening...