Stretched image on initial page

I created a new post with one thumbnail image aligned left at the beginning of the post, then added additional images placed them at the end of the post. I published it, then went to view site. It appears fine in the sidebar, but in the main content column it is a very distorted, stretched image that takes up most of the screen, and not the image I placed at the beginning of the post. I am VERY new to blogging so I’m guessing I have some setting messed up, but I don’t know what. I am using Genesis/Pretty Young Child Theme. It is the Cake Pops post on redrobinsblog.com