Tilly wet the bed twice and it was because her bladder was so full from drinking to much! so I took her in to the vet and ran tests, he had told me she either had diabetes which would cause the need to drink excessive amounts of water? or cushings disease. well the test revealed Cushings!
she is currently still has been on medication for this, but your baby is pretty young to have cushings it usually affects older dogs and tilly was dianosed a 6 years old she is now going to be 11 yrs. please check with this link as it will discuss urinary problems.
http://www.vetinfo4dogs.com/ddrinkandurin.html