"The day I realised there was something wrong with my vagina."

Image via Fox.

For Carly*, 32, the first sign something was wrong was when her ex-boyfriend Gavin* politely declined giving her oral sex.

After some pressing, Gavin, clearly embarrassed and apologising profusely, told Carly that things were a little “smelly” down there.

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The comment made her sober up immediately, and when Gavin told her that the smell got “really bad after sex”, she decided seeing a doctor was probably in order.

“My doctor performed a load of tests and I came back positive for Bacterial vaginosis, or BV, something I had never even heard of,” Carly said.

So what is BV? According Dr. Martin Ritossa, spokesperson for the Royal Australian and New Zealand College of Obstetricians and Gynaecologists, Bacterial vaginosis is caused when the vagina's bacterial flora is out of balance.

"Don't be too worried, it's an imbalance rather than abnormality," he said.

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"Normally, you've got both ‘good' and ‘bad' bacteria. The normal, healthy, protective vaginal bacteria known as lactobacilli usually keeps the other mixed bacteria in check. However, BV occurs when the ‘bad' bacteria overwhelm the ‘good'." (Post continues after gallery.)

While about half of all women with BV have no symptoms, for others, symptoms include a watery, white or grey discharge and a particularly strong odour – that can have a fishy or ammonia-like smell.

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Experts are not certain of what is the cause of the bacteria getting out of balance. However, certain things make it more likely to make it happen, such as when you're stressed, lacking in sleep, or, when you have a new sexual partner.

Dr Ritossa says the imbalance often clears itself up.

"However, I would suggest visiting your doctor, who will take a swab for analysis. If it's found that you are suffering from BV, usually antibiotics known as metronidazole will prescribed," he said.

Carly was given a seven-day course of antibiotics. The antibiotics were effective, and the smell disappeared completely two days into the course.

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It's worth noting that about half of all women with BV are thought to suffer from recurrences within six to 12 months.

The best way to keep your vagina bacteria in check? Dr Ritossa suggests is to live a healthy lifestyle – lots of sleep, good food, no smoking and exercise. Meanwhile, over the counter products such as Aci-Jel vagina jelly can relieve symptoms.