A few weeks before the 2010 U.S. Open, golf pro Phil Mickelson began to experience severe joint pain. even his regular practice routine suddenly became difficult to endure.

“I didn’t think much of it,” said Mickelson. “But I didn’t know what it was or what it could be.”

But 40-year-old Mickelson still couldn’t shake it. He and his family left for a vacation in Hawaii, where Mickelson’s aches and pains became so excruciating that he could barely get out of bed, never mind swing a golf club.

“I got really scared,” said Mickelson. “I started wondering what it was, and if it was even treatable.”

Mickelson immediately went to see a rheumatologist, who diagnosed him with psoriatic arthritis, a chronic, inflammatory arthritis caused by an overactive immune system. Symptoms and signs include stiffness, pain and swelling of joints, reduced physical function and reduced quality of life.

While athletic injuries can predispose people to early osteoarthritis, a degenerative disease of cartilage, there is no study that suggests sports predispose people to psoriatic arthritis, which usually hits those in their 30s and 40s.

Up to 30 percent of people who have psoriatic arthritis have had psoriasis, a common skin disease that causes itchy, dry red patches topped with silvery scales on the skin.

Mickelson said that he had psoriasis about eight years ago, and a dermatologist had treated him for it. After diagnosis, doctors put Mickelson on an individualized treatment program right away. Today, the golfer, who has won four major championships and 38 PGA titles, is back to his practice regimens and workouts.

‘On Course With Phil’

And on Wednesday, Mickelson launched ‘On Course With Phil,’ created in collaboration with Amgen and Pfizer, and the Joint Smart Coalition, which includes the Arthritis Foundation and the National Psoriasis Foundation.

The program is meant to educate peopl about chronic inflammatory conditions and encourage people to get checked if they have any symptoms.