If you are going to use the photo tag you should let people know this isnt your photo.
Not citing the source of photos (images) is plagiarism. Here is a post on why this is bad, and here is how easy it is to find allowed photos.
Not indicating that the content you copy/paste is not your original work could be seen as plagiarism.
If you are actually the original author, please do reply to let us know!
More Info: Abuse Guide - 2017.