Memories are malleable and ephemeral things, and so easily changed or even washed clean under the right, or perhaps wrong, circumstance.
A woman awakens in the woods, and her shape is smaller and weaker than she's used to. There are great clawmarks along her belly, around a greater wound, both still red and bleeding, but at last beginning to heal. It is healing slower than it should be, but at last things are set right, again. She is responsible for the clawmarks. There was a thing, a terrible and cold and itchy and awful thing, like she'd never felt before, and it had been lodged inside her. It's out, now, and lying nearby, a shard of shining grey against the bloodstained grass.
She remembers the hunt. She remembers her prey. She remembers being strong and fast and deadly, and the delicious taste of flesh on her tongue, and the terrible not-prey that hunted her, with its long and sharp not-claw that itched worse than fire burns.
Everything else? Well. That's a bit more difficult to say.