Biles said during a social media Q&A Thursday night that the problems are called the "twisties" ... and explained her mind and body just simply won't connect now during stunts.

"It's honestly petrifying trying to do a skill but not having your mind & body in sync," Biles said.

"Literally can not tell up from down. It's the craziest feeling ever. Not having an inch of control over your body."

Biles added, "What's even scarier is since I have no idea where I am in the air I also have NO idea how I'm going to land, or what I'm going to land on. head/hands/feet/back...."

The positive news -- if there can be any sort of thing given the situation -- is Biles said she's experienced all of this before ... and claims it usually goes away.

"Typically for me it's usually 2 or more weeks when I've had them before," the 24-year-old gymnast said. "Honestly no telling time frame something you have to take literally day by day, turn by turn."

Biles said getting back to the basics and working in a foam pit can help her get her bearings back ... and fortunately, she says she's found a place in Tokyo to work on all of that.

While Biles has withdrawn from two big events already at this summer's Olympics ... she can still compete in several more events next week.

Unclear if she'll be ready in time ... but she made it very apparent she's not going to risk her health going for more gold.

"For anyone saying I quit, I didn't quit," she said. "My mind & body are simply not in sync."