i use the same carefresh as you, and mine are ok for 2 weeks with little to no smell, it might dipend how deep it is and if yours use a sand bath for toileting.
5 days on carefresh would hardly smell and mine are right next to my bed.
have you disinfected the cage and checked food stores, they might be storing something that dosnt keep well like carrot cheese or any things like that.
I hope you can work out what the problem is
is it just with dwarfs (im bad at remembering who has what im afraid) my chinese barely smells and my WW constantly smells of popcorn.
if its strong amonia smell i would keep a close eye and maybe visit a vet. but if its with all of them its confusing what it could be