Re:Hampster bedding??
I do not think you should be surprised or upset that 5 days of peeing and pooping results in a smelly cage! I have had much experience having spent many years with all types of pets and this is just what they do. If you peed in the corner of your house for 5 days, it would also smell.
Even my bird cage needs cleaning out at least once a week! I have never had a gerbil, but hamsters and guinea pigs pee a lot. I used to buy the huge bags of cedar shaving made for kennel bedding at Walmart or the farm supply store.
A big bag would last me at least three months and I’d clean the cage out twice a week. Your local library or pet store has books on the care and feeding of hamsters. I would never restrict their food or water because it made them pee to much.
They are at your mercy and I know you want to take good care of them.
Kath