My puppy cannot control his bladder. PLEASE HELP!

by Hailey
(Texas)

I got a jack russell when he was 2.5 months old. I, along with my fiance and our families, have been working with him and training him properly, especially potty training. He has been awesome about going to the bathroom outside until about a month ago. He is 5 months now and he literally pee's everywhere. I don't think he even realizes he is peeing sometimes. He'll just be walking and peeing at the same time, and its ALOT, not just a little bit. I'm a certified Vet. asst. and I've studied this a lot, but i literally have no idea what this could be. Any feedback would be greatly appreciated :)