Hello,
Rest assured, everything you’re describing is completely normal for a 3-month-old puppy. He’s still right in the middle of learning about the world and his own emotions! :))
Regarding walks, at this age, your home and garden represent the ultimate "safe zone" for your puppy. The housing estate is full of intimidating noises (cars, strange smells, neighbours), which takes him out of his comfort zone and can be quite scary. Try not to pull on the lead, as this makes the walk feel like an unpleasant chore. To make the learning process easier, try teaching him to walk on the lead inside the house first, somewhere he feels "safe". Once he’s mastered walking on the lead, gently encourage him outside with treats to motivate him to move forward. If he stops, keep carrying him for a few yards as you’ve been doing to get past the stressful area. As he gets older, he should become more confident and start heading out of the house on his own. Also, if you have a friend with a dog, try going for walks together to reassure him and show him the ropes! :))
Now, for the nipping with your children, this is a classic puppy problem: he is exploring the world with his mouth and hasn’t mastered his "bite inhibition" yet. Plus, children generally move fast and squeal, which sends his excitement levels through the roof. When he nips, say a firm "no" and stop the game immediately. If he doesn’t calm down, give him a "time out" in a quiet spot for one or two minutes so he can settle. The need to chew is massive at this age. Offer him age-appropriate puppy chews or Kong-style toys to gnaw on; you can also stuff them to help soothe him and keep him occupied.
Finally, regarding playing fetch, this isn't innate for all puppies, even for a working breed like a Spaniel! For now, he’s probably just too focused on doing his own exploring. To introduce it slowly, try throwing the ball just a short distance. Roll it about a metre or two away from you in a hallway at home, for example. As soon as he picks it up, give him plenty of praise and call him back to you with a really tasty treat so he’s happy to do a "swap".
Take your time; these are standard stages that are easily sorted with patience and consistency! :))
Wishing you many wonderful adventures with your pup!
Best wishes,
Laure.
Translated from French