bacterial vaginosis

Janny
Hey guys 
So I was wondering if anyone know what bacterial vaginosis is and why it occur ? I had itchy and weird discharge since yesterday and went to my gyco today . She told me I got both bacterial vaginosis and yeast infection . I had no idea what cause it and she keep ignoring me when I ask about the causes 
FYI the last time I had sex was last Monday so I doubt sex is the cause