There are several medical issues that can interfere with potty training. Dogs with a urinary tract infection (UTI) will urinate frequently in small amounts, and will not have much control. You may also notice excessive licking of their genital region. If you notice a change in the consistency of their stool, the cause could be a gastrointestinal issue. Some common causes in puppies are intestinal parasites, having eaten something not in their normal diet, or a sudden food change. If a food change is necessary, do it gradually over 5 to 7 days. If you suspect any of these issues could be a problem, you should consult with your veterinarian.
It’s best not to punish the puppy for making a mistake. Instead, focus on praising appropriate bathroom behavior. If you catch your puppy in the act, interrupt it by saying “No!” in a firm voice or clapping your hands loudly, then take the puppy outside to finish going to the bathroom. Never swat your puppy, yell at it, or try to rub its nose in the mess.
I don't teach or recommend so-called "purely positive" methods that allow misbehaving pups to continue misbehaving, instead of teaching them which behaviors are and are not allowed. "Purely positive" is fine for teaching tricks and high-level competition exercises, but NOT for teaching the solid good behaviors that all family dogs need to know, and NOT for stopping behavior problems such as barking, jumping, chewing, nipping, chasing, etc.
Though it differs by each individual dog this is the time when most will come up with their own little way of letting you know they’ve got to go. It might be crying at your feet, ringing a bell you’ve set up or waiting at the door — just be sure to pay attention to these signals & follow up. Once your dog knows how to get your attention when he’s got to go you can relax a little and congratulate yourself on a job well done.
Young puppies can’t hold their bowels & bladders for long. If you come home to find that they’ve had an accident in there it’s quite possible that they can’t hold it that long. Generally puppies can hold their bladder for about one hour per month of age. So your 3 month old pup can probably only hold their bladder for about 3 hours. If you’re going to be away at work for long periods of time see if you can get a neighbor, relative or dog sitter to come over to let your pup out during the day.
Introduce your new pup to its new home, family and their role. Just like when you are new to a place or group, your new pet may be bursting with curiosity, excitement, fear or joy. Now is the best time to lay out the foundation for a good and pleasant relationship with your pet. For a puppy to settle in and learn to trust and respect you and everyone at home, it is very important to establish your expectations of your puppy and be consistent with them.