Missing Photos?

So I recently backed my phone up and restored this back up, but somehow I am missing 5000 pictures. Before this, my phone had 7000, but now it only has 2000. When I plug my phone into my computer, Itunes says there are 7000 pictures, but when I look in my phone, it only has 2000! I'd just restore an old backup, but I added a few songs from a CD and I don't want to go through that long process again.

I have an iphone 5, with the most recent update.