My male Jackadoodle (3yrs) has started barking quite aggressively at other dogs and people who walk past. He puts his back up and starts jumping in the air (not on the people). He is not an aggressive dog at all, he really wouldnt hurt anyone, when people do get close to him he cowers away or if another dog comes up to him while he is barking he will submit to the other dog. He didnt used to do this. It has only started in the last couple of months. It is just embarrassing and I am scared someone with kids will think he is really agressive and try to get him put down or something.

I really need help here.