Sometimes when mineral deposits build up on cloth diapers, they smell okay out of the wash, but then REEK of ammonia once a tiny bit of pee hits them. The smell of the morning pee diaper, since it's so pee-filled, can be almost overpowering. Susan informed me that this means they need to be stripped. (I also line-dry, but I live in an area with hard water, so minerals build up fast.)
So maybe try a disposable or another cloth diaper and see if that improves things? If it does, you probably need to strip your diapers.