Here's what you need to know about editing with Photoshop from within Photos:
1 - if you create a .psd file from a jpeg original you must save it to the desktop and import as a new file just like with iPhoto.
2 - if a jpeg is edited by PS resulting in a .psd file and it's saved without selecting the Desktop the default location will be here in a folder like this

AND the resulting folder and .psd file will be deleted automatically.
3 - if you flatten the file in PS and save it as a jpeg it will be saved correctly and recognized by Photos.
4 - if the original file is a .psd file and is edited by PS and just saved the resulting edited version will be converted to a jpeg file and recognized by Photos. Also if edited with PS a second time you'll lose the layers and just be editing a jpeg file.
5 - to keep the .psd file so you can do another edit first duplicate it and edit the duplicate file with PS. That will preserve the original .psd file and it's layers for additional edits even though the first edit will be lost to the second edit.
