Ahh, poor puppy. Congrats! My dog does the same. Here is why . . . I got the dog we have now in January during one of the worst winters we've ever had. We potty trained but didn't go for a lot of walks (it was seriously 20 below zero many days outside with windchill). Spring thaw, I took her outside. I walked up with her to a neighbors dog and she did the screaming thing. It's fear. Fear aggression is common. Your dog may have not been socialized or had something traumatic happen as a younger pup. Acting normally shouldn't be your goal but making your dog more comfortable. This comes with controlled exposure. Introduce slowly to other docile dogs. Hire a trainer would be even better. My dog never really got over it. I didn't realize about socialization with other animals as a puppy as I never had that issue before and never got a dog during winter when it was mostly inside with people and not other dogs/cats. My dog is a champ with kids! Loves them. Other animals? No sir. But socializing her or working through anxiety is the best bet to make your pup more comfortable and social.