Same thing happened to Bear. Dr took an ultrsound and decided that he has an overactive bladder and it is not filling up enough to get a strong stream, which makes sense as he does have urgency issues. Doctor gave him a gel to rub on shoulder daily, does not seem to help yet. BTW Bear is 4 month post RRP.
Suggest you keep in touch with your doctor in case it is a blockage.
CareBear