Hi, My Friend Had Protected Sexual Intercourse With Her First

Hi, my friend had protected sexual intercourse with her first and only boyfriend. She's also his first and only girlfriend. The next day after sex my friend, the girl, had a burning feeling or pain during urination. After days of drinking lots and lots of water, coconut juice and staying away from salty foods, the pain and burning sensation subsided to a minimum but she said that she still has discomforts during urination such as her clitoris "ringing" or tingling during urination. Today is the 2nd week of her condition without going to the doctor, now, she just told me that she found green mucus on her underwear which smelled bad and her "DISCOMFORTS" elevated. For example, this is what she said "I feel like my bladder is moving inside of me. I feel sore and a little bit itchy down there. And still, when I pee my clit rings or tingles". May I ask what are the possible causes of her condition and what she should do? PS. She also just had her menstrual period last week