Twisting your torso, you look back at your lower half. In your panic, you'd forgotten that your legs and feet were encased in the tight mermaid's tail. It flops behind you, awkwardly twisted, the tailfin propped up against the stall wall in the small space. You wriggle around and flip over, hands going to your hips to try to slide the costume down and off.
Something inside is telling you that you shouldn't be finding it strange at this point that you cannot seem to find the edge of the latex. Your thicker fingers dig into your skin, but the iridescent scales seem to meld into your flesh - there's no discernable line where the costume ends anymore! You're lower torso now resembles the ripped abdominals of a underwear model, and a defined V of muscle runs over your hipbones and disappears into the blue and green scales covering your crotch. You can clearly see a bulge in that region that wouldn't have been there under your panties, and you struggle not to fall back into the panic that almost engulfed you moments ago.
You're gasping, lying twisted up on the floor of the changing room in some strange costume shop, and you're starting to notice how parched you feel. You're scales are looking less shiny by the minute, their iridescence dulling as your chest heaves. A tickle below your jaw causes you to raise your hand, and you're now unsurprised to find what feel like gills on the side of your neck, flapping softly open and closed as you struggle to breathe.
All of these changes aside, your situation appears to be becoming more dire.
You reach for the door handle, only for it to...