IT took Bex 11 years to get an answer to her extreme pain - something she compared to sitting on a hot knife.
She had been in and out of hospital around 50 times before being told she had endometriosis.
The agonising condition, which affects 1 in 10 women, is caused when tissue from the womb starts to grow on other pelvic organs.
As well as extremely heavy periods, endometriosis can cause debilitating pain and sometimes infertility.
Although common - affecting 1.5million women in the UK, its symptoms can often be overlooked and it takes an average of seven years to get a diagnosis.
That was exactly what happened to Bex, who was initially told she had Polycystic ovary syndrome.
She's one of three women who have opened up to the BBC in a short film about their struggles with the condition.
Bex said: "My pain feels like I have sat on a hot knife," adding that on one occasion it caused her to "collapse in the street".
She added: "Being misdiagnosed made me feel really sad, helpless. I got told I had Polycystic ovary syndrome. [It has taken] over 11 years I've been hospitalised maybe 50 times.
"It makes me feel angry but also worried about all the other women out there that are currently struggling."
Being misdiagnosed made me feel really sad, helplessBex
Bex says the lack of knowledge around the condition makes her angry and "worried" for other women.
She questioned why there is so much research into other conditions, such as diabetes which affects 1 in 16 people, and not endometriosis.
"I think society doesn't take women's pain as seriously as they should a lot of the time," she said.
"There's so much research and funding around diabetes but why, if it's affecting the same amount of people, do we not having any more funding but behind it? We don't even have a cure yet."
Sadie also spoke to the BBC after she was told her pain was being caused by Irritable Bowel Syndrome (IBS).
She revealed that she's been left unable to use tampons because it's too painful.
Describing the agony, she said: "[It's like] putting your hand up inside you and someone's squeezing all your organs. I can't wear tampons because they're too painful."
It took 15 years before doctors realised she had endometriosis - and says there needs to be better education.
"I've seen doctors who have never heard of it.
"It's 16 years and it's only sort of been in the last 12 months they've mentioned this condition. I've seen in the region of about 50 doctors.
"Why is it during sex education you never learn about this condition?"
Heavy periods and 4 other signs of endometriosis – and how to treat it
1. Heavy periods
One of the main symptoms is painful periods – but the pain is often more severe than ‘normal’ period pain, and lasts from a few days before the period until the end of the period.
Many women also have low tummy and pelvic pain, which may be worse before and during a period but can be there all the time.
2. Pain during and after sex
Painful sex – especially during deep penetration – is also a common symptom of endometriosis. This can last for several hours after sex.
Penetration and other movements related to sex can pull and stretch endometrial tissue, especially if it has grown behind the vagina or lower uterus.
3. Difficulty conceiving
Endometriosis can also make it harder for you to get pregnant.
If you have endometriosis and are trying to get pregnant without success, it is important that you get help and support so speak to your doctor about being referred to a gynaecologist or a fertility specialist.
4. Bleeding between periods
Spotting between periods might not seem like too bothersome a problem but it can be one of the key signs of endometriosis.
A study published in the American Journal of Obstetrics and Gynecology showed premenstrual spotting is the clearest predictor of endometriosis.
5. Pain when you go to the toilet
It can also cause pain when you wee or poo and very occasionally blood in the wee or poo.
You may also experience fatigue, diarrhoea, constipation, bloating or nausea.
Another woman to speak out was Rebekah - also told she had IBS - who admitted the condition has caused her such agony she's been physically sick.
She described the pain as "like someone's getting a knife and just whipping it round on the inside. There have been times I've vomited just because it's so much on my body.
"It's ten years of the same symptoms just getting progressively worse and no real investigation as to why.
"This year? five times I've been in hospital A&A because of pain."
It's like someone's getting a knife and just whipping it round on the insideRebekah
She believes she shouldn't have to fight with their doctor for a diagnosis, adding that women are made to feel like their pain is natural.
She said: "Why there isn't more knowledge about this within health care professionals?
"I find myself a lot of the time explaining what Endometriosis is and how it affects me to doctors.
"I constantly feel like I have to fight. I'm fighting with my own body every single day as it is I shouldn't have to fight with the doctor."
Speaking in the short film, Professor Andrew Horne, consultant gynaecologist, said: "Endometriosis is a condition that affects women, whereby cells a bit like those in the lining in the woman are found outside of the womb.
"They bleed and cause inflammation and often this can lead to debilitating pain.
"It's estimated that one in 10 women suffer from endometriosis so that makes this condition as common as diabetes."
MORE ON ENDOMETRIOSIS
Last week, it was revealed that millions of endometriosis sufferers are plagued by suicidal thoughts and half of women with the condition are relying on highly addictive painkillers.
Most of the 13,500 people who took part in the BBC study said endometriosis had affected their education, career, sex life and mental health.
MPs have now announced they will launch an inquiry into women's experiences of the chronic condition.