What Causes Vaginal Gushes?

My mum is in her fifities and has recently started having what i can only describe as "vaginal gushes" for the past couple of montsh. They occur randomly every week or two and she suddenylu has a gush of watery liquid come out, with an odour. She has spoken to a Dr but we have not been succeufl in finding out what is is so far. any ideas?