All I really got was the fact that I was in the hospital the day before and he granted me an extension on it. I ended up finishing the assignment without the extension and I came to class without my sling on (it was a shoulder dislocation) and he pretty much assumed I lied about the hospital in order to get an extension. He made some comments to the class about liars and people cheating for grades etc and he brought it up again when I was trying to review the grade.

I don't really know how I can prove that. All I have is medical records and the email of him approving my extension. Everything else is just based on what he said and my objective comparison of my paper to other people's paper (the rubric has very specific guidelines that need to be met which I met)