She gets herself free.

As Brenda shifts and strains her muscles trying to free herself, little bits of dirt and pebbles rain down on her from above bouncing off her new form... Slowly, pressing her elbow and knee against the tunnel wall she uses the leverage to roll over scrapping her shell spines through the loam and rock before they finally come free. Puffing a bit Brenda wipes some sweat from her forehead. "Finally... Ugh... Now to get out of this weird cave."

Wiggling forwards Brenda crawls arm over arm to squeeze forwards though the tunnel fighting to push her massive form through the tight tunnel. After squirming through the earth for ages Brenda comes to a stop panting covered in grime as her arms and legs burn with the effort. "G-got... I gotta work out.. An whip this body into.... Proper shape once I get out of here... How long is this damn Tunnel!?" Growling she slams a fist against the ground with little effect, but... As her breathing calms down she starts to hear something with her raged breathing calming. With a bit of effort she starts to push herself forwards a bit farther.