Gaining her powers

Gwen woke up, her head spinning. What had happened yesterday? There was something about... a spider? Did it bite her? But she couldn't feel a pain from a bite.

She sat up in bed, wiping her bleary eyes. It must be early, for her to still be this tired. She looked at her bedside clock.

Gwen jumped out of bed suddenly. It wasn't early, it was very late! She grabbed some underwear from her drawer, pulled her blouse over her head, and stepped into her skirt.

The skirt went up, and kept going up until it wedged around her waist. But instead of stopping at her knees as it had yesterday, the hem now hovered only just below Gwen's ass cheeks. She also realised that although she had the waistband in place, the button was going to be a struggle to reach the hole.

"That's weird." Gwen said to herself, "My skirt shrank."