My dog is potty-trained..so why ..

Brief：
I have a 6 month old male pomeranian...he has been COMPLETELY potty trained for a month now.However, lately, despite the fact that Ive been taking him.. 

I have a 6 month old male pomeranian...he has been COMPLETELY potty trained for a month now.

However, lately, despite the fact that Ive been taking him outside to go potty more frequently...he has been peeing in the house a great deal. Hes peed on the couch several times now, and right in front of us. Just today he jumped up on the couch, peed, and jumped off. It is SO unlike him to act like this and I'm really starting to lose my patience.

He's been recently been neutered...which was when this started happening...but I dont see how being neutered could be a cause, unless there is something im unaware of.

Secondly, weve just got a new puppy...I may think that hes acting out like this due to jealousy if it werent for the fact that he loves the new puppy and they play together VERY well. They dont fight and he doesnt act jealous or upset by her.

Im basically wondering what the cause for this could be.and what I should do about it.

Any advice is greatly appreciated. Thank you!

He could possibly have a bladder infection whch causes them to urinate more easily and without control at times. You will need to take a urine sample to the vet to check it over. Then you can go from there to decide if it is a behavioral issue. You don't ever want to rule out the bladder infection, because if you've ever had one yourself you know how painful it is and wouldn't want to just wait. Most vets allow you to bing in your own urine sample fro them to run and then it is also cheaper then if they were to have to catch it. Good Luck He could be peeing to mark things as "his"; just because he *likes* the new pup doesn't mean he does not want to be your #1.