A woman who suffered intensely painful periods for some 20 years was finally diagnosed with a revealing ailment — helping to clear up a mystery that began plaguing her even before she became a teenager.

Jen Moore, 35, a former wedding cake baker, said she was unable to stand up straight when she first began experiencing painful periods as a girl of 11 years old.

She said doctors put her on birth control pills to try to reduce her periods, according to news agency SWNS — but that didn’t alleviate her pain over the years.

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She was informed by doctors that what she was experiencing was “normal,” she told the news agency — and that she was just someone who was “unlucky” to have painful menstrual periods.

But during the COVID lockdown, when she came off the contraceptives after 22 years, she said she “didn’t recognize the person she became” and would often pass out from the pain and blood loss.

When she went to a physician due to her menstrual pain and had an ultrasound, she was told that no endometriosis had been detected, she told SWNS.

Not satisfied, Moore, of Cambridge, England, paid on her own to have an MRI scan.

She was ultimately diagnosed with endometriosis and adenomyosis, conditions in which the lining of the uterus grows in places where it should not be.

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Said Moore, “At the time, I thought it was normal because I didn’t know any different.”

When she was young, she said, her mother took her to see doctors — and Moore said she was told that her painful periods eventually would stop.

“I thought it was normal because I didn’t know any different.”

She said doctors told her that even if she did have endometriosis, “all they would do is put me on the pill.”

She also said that today she still feels “rage” at what happened to her.

“I also feel heartbroken,” she told SWNS, “thinking about myself as an 11-year-old who had no idea she was about to go through so many of these things.”

She added, “I feel hope that generations are standing up and that they don’t want to tolerate this anymore.”

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Yet “I feel that it shouldn’t have to fall to the patients to do that,” she also said.

Moore said that even now, she feels “exhausted” and that there “isn’t an area of my life” that this hasn’t touched.

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She said that even though she had painful periods for so long, she wanted to go to college and try to live as normal a life as possible, “despite being bed-bound” for about a week every month. 

She has learned, she said, that she has endometriosis on her bowels and her bladder — “it’s everywhere again, it’s just relentless.”

She said she’s had “this condition damaging her organs for 22 years — that’s a lot of damage to unpick, so surgeries are never magic and [don’t] always provide a pain-free life.”

“Unfortunately,” she said, “there is still a lot of endometriosis for me.”

There is an “urgent need for greater awareness.”

Janet Lindsay, CEO of Wellbeing of Women, told SWNS, “Endometriosis is a condition that affects the lives of many women, often for years before a diagnosis is made … For too long, women’s pain has been dismissed or misunderstood.”

There is an “urgent need,” she said, “for greater awareness, early diagnosis, and better support for those living with the condition.”

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Last year, Bindi Irwin, daughter of the late Steve “Crocodile Hunter” Irwin, discussed her recovery from surgery following an endometriosis diagnosis. 

Irwin, 26, said her “inescapable” pain was dismissed by doctors for 10 years as she was tested for all kinds of diseases.

“I was tested for everything,” Irwin told People magazine last summer. “Every tropical disease, Lyme disease, cancer, you name it. I had every blood test and scan imaginable.”

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Endometriosis, according to the Mayo Clinic, is a condition “in which cells similar to the lining of the uterus, or endometrium, grow outside the uterus,” as Fox News Digital previously reported.

“Endometriosis often involves the pelvic tissue and can envelop the ovaries and fallopian tubes.”

The condition can be severely painful for those suffering from it — and it can impact fertility and menstruation.

Lauryn Overhultz of Fox News Digital contributed reporting.