Why do my photos come back after deleting them?

So recently I have been unable to delete photos from my camera roll. I press the delete button and the photo disappears for around 5 seconds then comes back. I can also not take any new photos. I can take the photo and it sits in my camera roll for around 5 seconds then it's gone when I come back it's like my camera roll is at a stand still. I can't post any photos on Instagram or Twitter as it just crashes the apps. I've restarted my phone and nothing has happened. I have tried backing up my phone but it says there's no photos to back up. My iCloud storage has suddenly gained back exactly the same amount of storage space as my photos took up even though my photos are still present on my phone. And when I click manage storage settings it says how much storage each app takes up apart from the camera roll. It's kind of frustrating because my camera and social media apps are basically unusable. Would appreciate some advice or some help many thanks :)