Jimmy Walker has revealed he is battling Lyme disease ahead of this week's Texas Open.
Walker, 38, opened up about the diagnosis (which is typically contracted via bites from ticks), saying he hasn't "felt good" since Thanksgiving.
The 2016 US PGA champion, who has been struggling for form so far this season with just one top-10 finish since October, announced at the Masters two weeks ago that he was feeling "sluggish".
"How long I've had it? I don't know. I know I haven't felt great since about then," Walker told the media.
"Been talking to some doctors, trying to figure out the course of action to take and get on some meds to get it going in the right direction."
Lyme disease is a bacterial infection spread to humans by infected ticks, which are tiny spider-like creatures found in woodland and heath areas.
"Basically feels like you got the flu," said the 2015 Texas Open champion. "No strength, just got nothing.
"And it comes and goes in waves. You never know when it's going to pop up."