Story with an experiment going out of control

Story by carb21

For the idea I have, meaby this story should have at least 2 or 3 chapters.

A girl participated as a guinea pig in an experiment for a new medicine that should cure inferility in women (Obviously the girl was sterile). But the experimente went wrong and she had her vagina replaced by a huge cock and balls, becoming a shemale. This is also infectious since every woman she fucks turns into shemales as well.

Meaby if the writer wants to go far can add the fact that some months after, just after becoming pregnant, they discover that the changed women still have their wombs, just that it's attached to the ass now.