Have you had Colby checked for a UTI? He might have one if he is peeing all over the place while playing. If not, he might be backstepping for a bit. A lot of puppies do that. You will just have to start training him over again.
My puppies also went through a stage where they decided they didn't like the food I was feeding them. The lady at the pet store told me her yorkie does that on a regular basis, where they decide they no longer want what they are being fed and you have to find a new food for them. Our 8 month old is on his 3rd food already. When he stops eating his food, the 6 month old stops eating her food because she wants whatever her brother has.
Please don't think that your puppy might not be a purebred yorkie just because he weighs 7 lbs. already. There are many 'teapot' yorkies out there. In fact, my puppy is one. He is 8 months old and weighs 11 lbs. I just think there is more yorkie to love and snuggle with
