The Heart of the Thicket by Kennedy Sutton

The woods were never something Odell Raleigh feared until her husband vanished in the Appalachian forest surrounding their home. With winter closing in, their young daughter to care for, and her savings running low, Odell’s struggle to keep destitution at bay consumes her every thought.

When their 4-year-old daughter, Anne, becomes stuck in a mysterious time loop in those same woods, Odell is dragged into a secret world known as The Thicket.
With the companionship of a wisp named Fallow, facing The Thicket’s mysterious and dangerous creatures is the most frightened Odell has ever been. That is, until she discovers they aren’t the most terrifying part. Every moment closer to her goal means a memory of her daughter vanishes from her mind.

Odell needs to get through The Thicket and win the race against her fading memories before Anne is lost forever, but time, and Odell’s mind, are running out.