Teufelhunden

I have a 4 month old Shepherd Neewa, He is a sweetie, but when he is excited he pees, when he comes in from outside site to be pet he pees.. what is up with this? and for being 4 months his little member keeps making a showing when he is peeing? Kind of puzzling as he is wagging his tail and licking me but peeing... Also he seems to lick excessive to the point where it is not cute anymore it is constant... He was abandoned when he was very young and we got him at 2 months old. Any input would be appreciated, thanks, Chris