I just found it...
Go to the Specific Trip, on the page where you can edit the story,tips, tags, and below that is photos.
Go to the photos section (NOT EDIT), but rather the hyperlink that is blue and underlined " See all pictures and videos from [NAME OF TRIP]"
There it will take you to the Trip photos click on the one you want to rotate.
It will open the photo, and on top there is a button called EDIT PICTURE, click on that and it will take you to a page where you can rotate the individual photo. hit Save and your done.