Dwayne “The Rock” Johnson recently got a scare that would rattle just about any man.

While showering one Friday night, the 54-year-old actor and professional wrestler discovered a painful lump on his left testicle, sending his mind racing.

Days later, his doctor told him it could be one of two things: epididymitis, a common inflammatory condition, or cancer.

But with a full day of “Jumanji” promotional appearances on his schedule, Johnson had to wait until the following morning for an ultrasound. Until then, all he could do was wait.

“I had to live with that for those twenty-four hours, not knowing — and I had to be on all day, joking around, making speeches,” the “Moana” star told Esquire in a recent interview.

“By the way: I’m fine,” he said. “But I didn’t know that then, and the thing was really painful.”

Fortunately, the lump turned out not to be cancer. Johnson was diagnosed with epididymitis, which affects roughly 600,000 men in the US every year.

Here’s everything you need to know about the condition — and what to do if you notice a concerning change down below.

What is epididymitis?

It’s an inflammation of the epididymis, a small coiled tube behind the testicle that stores and transports sperm. 

While it’s relatively common, experts say most men have never heard of the condition.

“When they develop pain, swelling or feel a lump, many guys immediately worry about testicular cancer or another emergency like torsion,” Dr. Jamin Vinod Brahmbhatt, a board-certified urologist with Orlando Health, told The Post.

“I’ve had epididymitis myself, and the pain can be pretty intense, so it’s understandable why people get concerned.”

What are the symptoms?

“The most common symptoms are pain, swelling and tenderness on one side of the scrotum or ball,” Brahmbhatt said. “It may feel like a worm around your testicle.”

Some men experience urinary symptoms, including pain while urinating or a frequent urge to go. Others may notice discharge from the penis or even blood in their semen.

Pain can also spread into the groin, lower abdomen or pelvis. In some cases, men develop fever and chills.

What causes it?

Among younger, sexually active men, sexually transmitted infections such as gonorrhea and chlamydia are the most common culprits, according to the Cleveland Clinic.

For men over 35, epididymitis is more often caused by bacteria that travel from the urinary tract into the epididymis. E. coli is the most common offender, although other infections — including mumps and tuberculosis — can also trigger the condition.

Less commonly, epididymitis can result from a blocked urethra, a prostate infection, a groin injury, catheter use or even certain medications.

Can it be treated?

Yes — but the approach depends on what’s causing the inflammation.

If bacteria are to blame, doctors typically prescribe antibiotics. Without proper treatment, bacterial epididymitis generally won’t resolve on its own.

Most patients begin feeling better within a few days of starting antibiotics, although lingering discomfort can sometimes last for weeks or even months.

To ease symptoms at home, doctors often recommend rest, scrotal support or elevation, ice packs, plenty of fluids and over-the-counter pain medication.

In cases linked to medications — such as the heart rhythm drug amiodarone — physicians may lower the dose or switch patients to another treatment.

Severe cases are rare, but surgery may sometimes be necessary to remove one or both epididymides or, in extreme situations, a testicle.

Can it lead to complications?

“If left untreated, epididymitis can lead to chronic pain, persistent swelling and occasionally more serious infections or fertility issues,” Brahmbhatt said. “The good news is that most cases respond well when diagnosed and treated early.”

What should men do if they experience symptoms?

“I think every man should know their normal anatomy,” Brahmbhatt said. “You don’t need to obsess over self-exams, but if you know what’s normal, you’re more likely to notice when something changes.”

“Any new pain, swelling or lump should be checked out, and sudden severe pain should be treated as an emergency because conditions like testicular torsion need immediate attention.”