Unable to delete synced photos off iPhone and other photo issues

My original issue was that when I synced my iPhone [5c, iOS 8.3] with my computer [Macbook Pro, OS Yosemite], many-but not all-of my photos would duplicate an disappear from my camera roll. Well I managed to fix the duplicates issue. However, my new problem is that now I cannot delete or edit any synced photos off of my phone. The issue of the photos not appearing in my camera roll has still not been resolved as well. I'd really like to continue using the "camera roll" and "albums" feature on my phone as well as be able to see, edit, and delete any of my photos from the camera roll. I'm at a loss of what to do. HELP