Jason Day collapsed with vertigo coming down a steep hill during round two of the US Open at Chambers Bay on Friday.
The 27-year-old Australian, who suffers with the condition, needed treatment for a few minutes after his fall.
He regained his footing and missed a putt for par on the ninth hole - his 18th - before succeeding from four feet for a bogey to leave him on two under.
Medical staff had to help him walk over to sign his scorecard but Day said he plans to play on in the tournament.
Day's agent Bud Martin said: "Jason was diagnosed to have suffered from Benign Positional Vertigo. He is resting comfortably.
"His condition is being monitored closely and he is hopeful he will be able to compete this weekend in the final rounds of the US Open. He wants to thank all who treated him the fans and friends who have reached out to him and his family."
Playing partner Justin Rose, who shot a level-par 70 to stand at two over, said: "At first I thought he might've just rolled his ankle but then when I saw his caddie with a towel round him, I realised it was something else.
"I knew he'd been having some health issues recently and then that's when your mind starts racing a little bit."
Vertigo caused world number 10 Day to withdraw from the World Golf Championship in Ohio last year and last month's Byron Nelson Championship.