The skin will go back to normal. Cortisone can cause the skin to shrink--temporarily. Then the effects wear off and the skin grows again. It takes 6-12 months in most cases. Lying on it or stretching it won't have an effect one way or another. If you wait it out, you should be fine.
If the skin hasn't gone back to normal by a year from the injection, that's when you should show it to someone. But I bet you won't have to.
Best.
Dr. Rockoff