The four-time major victor has been far from his best over the previous year as he struggled with the injury he picked up in the close season, and has admitted to rushing back before regaining full fitness.
Alternate and World No. 156 Scott Brown orchestrated a 1-under-par 34-36=70 in the third round of the 99th PGA Championship to post 2-under 211, up four spots to T7, five adrift of 54-hole leader and fellow Aiken, South Carolina, resident Kevin Kisner.
McIlroy, 28, won in May previous year at the Dubai Duty-Free Irish Open before claiming titles twice in three starts at the Deutsche Bank Championship and Tour Championship in September.
Winless this year and having battled back and rib injuries, McIlroy suggested his 2017 could be over, but the Northern Irishman is unsure what his immediate future holds.
"So I hit a six iron and just said, "okay, I'll bounce it up the cart path and see where this goes".
"I thought conditions were just as tough, if not tougher this morning, as they were yesterday", said McIlroy, whose only major victory when trailing after 36 holes came when he was two behind in the 2012 US PGA.
McIlroy said the pain is not almost as severe as in May at the Players Championship when it flared.
McIlroy paused for the longest time. "The next big thing is April, and that's really what my focus will be on from now until then".
April is the Masters, the only major keeping McIlroy from the career Grand Slam.
"It's tough. I want to get back into that winner's circle", McIlroy said. "That is not where you want to be".
"As I said, I have a good bit of time to get healthy and address a few things going forward". That's the next big thing on my radar.
McIlroy revealed that he has felt spasms in a muscle in his upper back the last few weeks, and he's not sure when he will play next.
"I feel like I have a sense of, not duty, but I've missed a lot of time already". If I was injury-free, that wouldn't happen.
The play-offs get under way with the Northern Trust Open on August 24 and McIlroy is the defending champion of the Dell Technologies Championship the following week. That was basically seven or eight weeks.
"I switched it off for a couple of weeks because I was getting married, going on honeymoon".
"I can feel it", he said. Then once I started practicing again, I didn't build up the volume gradually. "I warm it up, it's OK", McIlroy said. That aggravated it a little bit. After his round, he intimated that he still doesn't believe he is fully healed. I wanted to play the season and I feel like I'm capable of playing well and winning and putting rounds together. "If I want to challenge on a more consistent basis, but I need to get 100 percent healthy".