PGA Tour rules official Mark Dusbabek said on the telecast that Woods had an illness, and that it was not related to his ankle or back.
Woods was one-over par for the round and projected just outside the cut when he asked for a cart and was driven off the course by a rules official.
Woods had not played an official event since the Masters last April, withdrawing in the middle of the third round of the rain-delayed major. He played the unofficial Hero World Challenge in December against a 20-man field with no cut, and the 36-hole PNC Championship with his son.
Woods had said he hoped to play one tournament a month through the major season. He had said Thursday he was experiencing back spasms, which led to his shank on the final hole.