'When a good boob goes bad.' The photo showing an unspoken dark side to breastfeeding.

A breastfeeding mother has opened up about the painful condition that shocked her, despite her training as a birth doula: mastitis.

“It literally feels like someone kicked me in the breast,” Lindsey Bliss told Cosmopolitan magazine.

The mum of seven shared her struggle with the condition – breast inflammation that can lead to a bacterial infection – with a recent post to Instagram showing her reddened breast.

A post shared by doulabliss (@doulabliss) on Mar 5, 2017 at 6:43am PST

Lindsey, from Queens, New York, told her followers she almost went to the emergency ward of a hospital because she was in so much pain, with flu-like symptoms and a swollen breast.

“When a good boob goes bad – AGAIN! I literally wanted Dan to bring me to the ER last night due to the most EPIC engorged boob, full body shakes, and a crushing headache.”

“On the mend today from my bed. Why does this keep happening?”

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Mastitis can occur when a milk duct becomes clogged and lead to infection. This can be caused by missed feeds, a baby’s poor attachment to the breast or even an overly tight bra, according to The Royal Women’s Hospital in Victoria.

The hospital recommends women try a series of treatments before seeking medical attention if the condition does not improve and infection has occurred – such as in Lindsey’s case.

It’s a condition that, only back in January, former Married At First Sight star Zoe Hendrix found herself grappling with.

Lindsey told Cosmopolitan she wasn’t prepared for the havoc mastitis wreaked on her body.

Me and my chicken little.

A post shared by doulabliss (@doulabliss) on Jan 24, 2017 at 10:26am PST

“No one really warns you about how powerful mastitis is,” she says. “Your boob can cause a full body shut-down.”

Lindsey said she shared the post not to frighten other mothers, but to show a different side to breastfeeding.

“You always see these flawless goddess photos of breastfeeding, and no one discusses or shows when shit gets crazy,” she told the magazine.

A post shared by doulabliss (@doulabliss) on Jan 6, 2017 at 5:15am PST

“Yes, [you might think] breastfeeding is the best thing for your child, but it isn’t always unicorns and rainbows.

“Sometimes it just sucks.”