I'm 16. As I turned 15, my mother got us a dog. I always wanted one and so she wanted to make me a present. She got us a german shepherd, which is my favourite breed. As first-time dog owners, my mother also never owned one, we probably should have choosed another breed but she thought that I'm not going to have any troubles with this dog since I had a good bond with the really, really difficult Weimaraner that my father owned. The dog actually wasn't supposed to be difficult or something. She got him from a local breeder who actually bred good dogs who he also trained a little bit before selling them. He said, that this dog is an absolute angel. We believed. Mostly because he was the most beautiful dog that I have ever seen and he looks like he wouldn't hurt a fly but we were proved wrong. We also own cats. As he arrived, the cats fell immediately in love with him, they adored him and he also loved them. They cuddled, they played with each other. He was 10 weeks old as we got him and he behaved like an angel the first 4 weeks. And then he suddenly changed. It all started with him getting aggressive towards the cats or that he started barking at every single noise he heard, no matter how loud it was. We were confused but didn't thought anything bad. And then he also started getting aggressive towards my mother and me. He growled at us and snapped at us. We went to a vet because we thought he maybe is in pain or something, but the vet said that he is completely healthy and fine. So we were left confused and worried. Then he started being so aggressive towards the cats, that he tried to bite them whenever they came to near to him. This leaded me into separating them when nobody's at home. We live in a house with 2 floors and so I lock the cats in the first and the dog in the second floor. As he was around 20 weeks, he also started biting us. He managed to do this one time at me. Again, we visited a vet with him but the result was the same; he's healthy and fine. As he was 7 months old, we spayed him but nothing got better. He's getting more bigger and aggressive every month. But the thing is; whenever someone comes to visit us, he behaves like an angel. Or when we were outside with him or at someone elses house. But when he sees a person too often, he also starts to be kinda aggressive towards them. Like he's getting bored of them and then just wants to never see them again. He sometimes starts to whimper when I touch him somewhere like he's in pain but when our guests touch him on the exact same spot he's enjoying it? The vet also said he's definitely not in pain there. He's already a big problem for me. I don't hate him, but I want to get rid of him. But my mother still has hope in him and wants to keep him. I'm already afraid of him. We visited a dog school with him, we spend so much money at the vet with always the same result, we hired a dog trainer but nothing helped. I don't know what to do anymore.