Suggest Treatment For Persistent Vaginal Thrush

I have had vaginal thrush for about 2 weeks now! I have bought the passery and cream and used it as directed. When I stop using the cream after I have used it for a week about 2 or 3 days later the itching comes back and it ends up being sore again so I end up putting more cream on. I'm not sure what I'm doing wrong. I have had thrush before about a year ago and it cleared up straight away. Why is it not working this time? What should I do?