Hi there. Firstly, we need to know more as regards the sexual history/contact history etc. Yes if she says she had contact with a man with similar symptoms, it is most likely an infection. Whether an STD
or not cannot be confirmed sans tests but those are the standard infections u refer to. Any infection contracted as a result of sexual activity qualifies as an STD in textbooks. Please have your sister visit a dermatologist
& /or if she desires discretion, can find me on this portal using the 'ask-a-doctor' icon & will do my best to help her further. Cheers!
Dr Praveen RodriguesMD
Dermatologist, Cosmetologixt, Venereologist
Vikram Hospital, Bangalore, India