Did you set up camera upload for Dropbox or Google Drive? iCloud is the default one, so if iCloud doesn't have what you want and you don't have another photo storage place setup, they are gone.
As a long shot, did you do backups of your iPod occasionally? If so it would have the photos up to the last backup. You would have to restore the backup to a new iPod, unless there is a way of opening the backup directly. Under iTunes open preferences and look for the devices tab. It will show the last backup, if it exists.