Oops!!!

Since the 12 hours were up he decided he'd change back to his older self.
Not that there was much difference but he liked his tattoo.
This time he wanted to see if he noticed any change so he went to the bathroom down the hall.
Where he took off his clothes to watch the small changes in the full length mirror.
He pulled out the medallion and was just about to touch it to the shirt he wore yesterday when it happened.
He heard a knock at the door which startled him.
He had been daydreaming about the possibility of having the perfect body without the hard work.
Any way the knock at the door startled him and made him step back quickly. Unfortunately for him the medallion he was holding touched the clothes basket.
That's when he felt the shock and snapped back to reality, and just his luck the last person to have put clothes in the hamper was his 16 year old sister Melanie.
He heard the knock again but this time followed by his mothers voice asking if he was ok.
He said he was and explained that he tripped when getting into the shower and that was the noise shed heard.
She replied just be careful ok.
That's when he started to feel weird.
The first time he barely changed at all, but unless he missed his guess it would be hard to hide this.
He heard his mom say goodnight and that her and his father were going to bed.
He was relieved to hear that maybe this mistake could be hidden after all.
He looked back in the mirror and noticed he had started shrinking.
That wasn't all though; he decided to turn the shower on to make it sound like he was taking a shower.
Then started watching the mirror again.
With the fascination of a little kid seeing mickey mouse for the first time.
Slowly he watched as he stopped shrinking at around 5"5".
Then he saw that he appeared to be losing weight.
He watched as his arms became less muscular and then thinned out.
He watched his fingers lengthen a little and become more slender.
The next thing caught him off guard. Some of the fat that was left relocated it's self.
He watched in amazement as it looked as though his skin was crawling. Kind of like when the scarabs got under that guys skin in the mummy.
It slowly moved around to his rear. Then he noticed it gathering and forming an incredibly feminine rear.
He wasn't a perv or anything but he had to admit his sister had a perfect butt.
Not too big but noticeable.
After his butt had finished forming. He felt the all too familiar feeling of his skin crawling again only this time going higher not further down.
Thats when he noticed how big his nipples seemed.
They must have changed when he was looking at his new ass.
Slowly but surely he could tell his chest was getting bigger.
It stopped when he was around a B-cup.
That was a weird sensation having his own set of breasts.
That's when he pinched his left nipple a little and shivered he didn't realize just how sensitive they can be.
That's when the pain started it wasn't excruciating but it was painful.
He felt as though his inside was on fire.
He felt a crack in his back and just like that his back arched a little bit to show off his new ass.
Then he felt his waist being pulled in and his hips expanding a little.
Finally the pain had receded and he was able to look into the mirror again where he saw a budding young lady's curves but with one slight problem.
Little did he know that problem was about to be solved.
Then all at once he doubled over in pain; this pain was like nothing he'd ever felt.
It felt as though someone kept kicking him in the balls.
Then he felt his testicles being pulled inside him, forming what would be his ovaries. Then his penis began to shrink. This didn't hurt nearly as much.
He was actually able to watch this happen the just like it had begun in the womb so many years ago his penis disappeared leaving a slit which was now his pussy.
Once that was through he knew it was almost over.
Finally he watched as his face began to contort. His eyes grew a little bigger.
His jaw became a little less sharp.
His brow receded a little. His cheekbones seemed to poke out of his face. Then his lips felt like someone was inflating them.
He thought they were going to burst. Then it stopped and what he was left with was the identical body of his younger sister.
at first he was ashamed to be seeing his sister naked.
Then he said well technically it's not my sister.
Having finished, and knowing he can't change back for another twelve hours he decided to go into his room and go to bed since he was tired from the transformation.