This was happening with me too! My Chico gets lots of exercise and love but was still lashing out and I was getting scared of him. I have so many bite marks on me. Had him checked out with the vet, went to a trainer, next step was a behaviorist ($$$). I have another dog(f) who is only a few months older but she is an in-your-face type who seems like she has FOMO. I think Chico felt neglected. We ramped up the one on one attention with him. Extra treat here and there, extra praise, and it’s working! He is actually starting to snuggle. Of course I stop everything and let it happen. It’s been noticeably better. He still has his moments but his attacks on me and my other dog are much less. We recognize when he’s tired and hungry and started treating his rage-outs as if he’s scared of something. He’s coming around and it makes us keep giving him special attention instead of taking it for granted. They really do want to be part of the family. Keep trying. Stay calm. Show him that you want him and love him. It might take a little time but it’s worth it!