[cypher]

It could be just the fact that the cage is small & it does also sound like attention seeking behaviour, it's not unusual for them to do that & it's best to ignore it as much as possible & only pay attention when they stop but with the small cage you have now I would just keep doing what you're doing until you can upgrade, most likely with a larger cage & plenty to do he'll get out of the habit.
Don't clean his cage too much, that really stresses them out, just spot clean & not much else for quite a while.
When you get the new cage you don't want to have cleaned the old one for a while so you can use the substrate & transfer it with his scent to the new cage.