My dog is generally a great dog. The only issue he has is pretty bad. Only when at home, usually on the couch, he lashes out when he is startled. It could be a motorcycle, fireworks, neighbors pulling garbage cans to the street, or a fly buzzing around the room. It also happens when I (female) cry (I have a chronic illness that causes a lot of pain). His reaction (his name is Iggy) is that he jumps on me or my husband and barks loudly in our faces, scratching as he goes. He’s nuts. If you try to contain him, it gets worse. We tell him "no!" And put him on the floor to get him to calm down but not much works until he snaps out of it. How can we get rid of this issue? I’d like him to feel calmer. In general he is a bit nervous, has been since we got him from the shelter. What can I do to boost his confidence and help him not lash out?