First, I would say, at 5 months, she should be eating a bigger meal than what you are feeding, unless they are big rat pinkies. To judge the size of the meal thats appropriate, look for the thickest part of your snakes body and keep in mind you can feed prey thats 1.5 times the girth at the thickest part. If her meals have been rather small, she wont be going to the bathroom as much cause she is digesting what you feed rather than have much waste.

Sorry, from the pics I cant really tell the type of injury you are referring to, however, what you describe reminds me of a bite mark thats healing potentially. What was she eating before you got her?