SAN ANTONIO, Texas – Since Thanksgiving, PGA Championship winner Jimmy Walker has battled fatigue. He’s suffered a loss of strength. And his normal happy disposition has given way to bad moods and irritability.

On Wednesday, he revealed why. He’s suffering from Lyme disease.

Tests taken the Wednesday of Masters week came back positive for the disease, a bacterial infection that infects approximately 300,000 people each year in the United States. Walker thought a couple of weeks ago that he had mononucleosis, but further results confirmed the Lyme disease diagnosis.

“We’ve been talking to a lot of doctors,” Walker said on the eve of this week’s Valero Texas Open, an event he won two years ago. “I think that was more of what was going on as opposed to the mono.”

Walker has consulted with his doctors on the next course of action, which will include antibiotics. He underwent further blood tests on Monday, and must wait until all the information has been evaluated before starting his meds.

“Hopefully we get to start here pretty quick,” he said.

One thing he’s hoping to avoid is taking a sabbatical from the PGA TOUR. He remains committed to playing through whatever issues he must face, and doctors have yet to prescribe rest. He did say, however, that had he started his meds this week, he might have been forced to withdraw from his hometown event. Walker lives in Boerne, about a 35-minute drive from TPC San Antonio.

“I heard it can take it out of you pretty bad for four, five days,” he said. “… Anybody knows me, rest isn’t something I’m really good at doing.”

Although Walker first noticed the symptoms in November, he isn’t sure if that’s when the disease first kicked in. He acknowledged he doesn’t know much about Lyme disease, other than he got it from a tick bite. The lone star tick, which can be found in parts of Texas, isn’t a primary carrier of the disease but could transmit a mild form. Hard-bodied Ixodes ticks, also called deer ticks, are considered a main transmitter.

After Thanksgiving, Walker played in the Hero World Challenge, where he tied for 13th (out of 17 players). Since the start of 2017, Walker has made 10 starts, despite feeling the effects of a disease he didn’t even know he had. During that time, his lone top-10 finish was a tie for ninth at the limited-field SBS Tournament of Champions, which he followed with two missed cuts.

Walker said the disease “feels like you’ve got the flu. No strength. Just got nothing. And it comes and goes in waves. You never know when it’s going to pop up.”

He said The Honda Classic was a “rough week” -- making his tie for 21st impressive. During the Masters, he actually felt decent, relying on Advil and other anti-inflammatories to help him compete. He finished tied for 18th, shooting three rounds of par or better after an opening 76.

Even during Wednesday’s pro-am round, his energy level was inconsistent. He started out feeling ill, then regained his strength for a couple of holes – and then, just as quickly, saw it disappear.

“I can’t figure any rhyme or reason out,” he said. “I’m ready to get over it. I know that.”

Close acquaintances are probably feeling the same way. Walker acknowledged the combination of an energy decrease and the frustration of not knowing why it’s happening have dampened his moods. It has even impacted his home life -- his children want to play with him, but he just feels like a rock, unable to coax his body to join them.

“It puts you in a bad mood. … It’s not real fun, honestly,” Walker said. “I think everybody out here would say I’m kind of a happy-go-lucky guy, smiling, having a good time. Some of my close friends have seen a little decline in that. …

“I haven’t really said anything to anybody about it, but I just keep plugging along.”

Patrick Reed wasn't aware of Walker's health issues until Wednesday afternoon, but he certainly hopes his Presidents Cup and Ryder Cup teammate returns to good health.

"You hope the best for all players," Reed said. "You hope they're all healthy and they can come out and play -- and play to their full potential and the best they can.

"I mean for Jimmy, I hope he can come out and play some good golf and also get healthy. Anytime you get diagnosed with anything, it's a scary moment. The good thing about here out on the TOUR, we're all kind of a family, so we're all pulling for each other -- especially when it comes to health."