Help Daisy get the life she deserves

This is Daisy, shes a 3 month old German Shepherd pup. She is having a hard time breathing, I’ve taken her to the local vet, that said it was only allergies, like humans they also wheeze and it was nothing serious to worry about, so they just prescribed medication. Un eased, i took her to the nearest pet hospital and I believe they took my money witout any reguards of the puppy in distress. The Dr who saw her obviously knew her breathing wasnt right, they even put us in a separate room saying that she might be contagious to other dogs. There’s no fever, shes around other dogs like the litter she came from and all other pups are fine. They adviced they needed to do an xray to rull out her breathing complications, they also did a sonogram of her heart. The Dr. came back saying her trachea looks narrowed which may be the cause of her difficulty breathing, that it is rare on a German Shephered. He informed us he was unable to concor the diagnoses the radiologist was the one who needed to confirm the findings and signed off on it. If that was the case of it being tracheal stenosis that there is no cure she’ll probably grow out of it but if not then its best to put her down instead of living a rather difficult life. They also advised i can see a specialist or internist Vet who can further help this pup have a better life we would just have to wait for the radiologist to cofnim. They called me a few days later stating the radiologist signed off on the xray saying he saw nothing wrong anf the dog is fine, but if she gets worst to bring her back in. How are going to tell me one thing and later say shes fine knowing she was in distress, they heard that her breathing isnt normal, basically not giving me the option to see if shes going to be ok or shes going to die from just walking. Now i need a second opinion or i have to go to the animal internist Dr and get a valid opinion since the hopsital gave me two different answers. We all know how expensive they can be, please help to try to get her seen and diagnosed properly to give her the life she deserves.