I'm hoping to get some insight from other corgi owners on some behavior changes I've noticed in my two year old neutered corgi, Einstein. I hate seeing Einstein behaving like this. This is NOT the dog I know and love. :(

In July, we moved into a new house.The new house has hardwood floors, which the dogs will slip and slide on when they run too fast. I also noticed that Einstein wasn't getting much traction when he tried getting on the couch, so he would essentially clothesline himself when he tried hopping up. I have since bought a rug for under the couch and that has significantly helped with Einstein trying to get on the couch, as he gets up on the first try now. 

The other big change with the house is it has a backyard (we were originally in an apartment) where I can let Einstein potty / practice his agility, etc. We still go on a daily walk and I exercise him in the yard by throwing frisbees, which he loves!

Around the same time, we also brought home a new corgi puppy, River. He and River will play, and they have plenty of toys that they share without issue, and River is great about submitting to Einstein.

What I have noticed is that since mid-July, Einstein is constantly on "high alert'.

• He waits for River to get into trouble. Even when I use a happy tone to call her to come or her name, he will search her out and mouth her neck or push her over.
• He is always listening for trespassers outside. He now barks at the neighbors walking past our house (with and without their dogs) and will bark in the yard if he hears other neighborhood dogs barking. This "new" bark makes him sound bigger than he is and makes him sound very aggressive / territorial. In our apartment, people would constantly walk by or make noise outside and he never barked at them.
• He is now sensitive to being petted and no longer enjoys tummy rubs. He will still let you pet him on the head and back. When you try to pet his belly, he will growl and bare teeth before licking your hand.
• Einstein guards his food - but only with River. I can walk up to him, put my hand in his bowl and pick it up without protest. Most days, he tries to bury his food with his nose and will just lay down by it without eating. River is fed and stays in her crate during the day, so there is no chance of her even getting to his food.

I have already spoken to my vet, who did a physical exam with no protest from Einstein, and she suggested I tried reinstating the "order" of my pack so that I am #1, Einstein #2, River #3. I have done that with feeding order, putting on leashes, etc. but I'm not sure it's changing anything. As of right now, we haven't gone back to the vet to address this issue.

I'm not sure if it's just him adjusting to the changes in his environment (new house / new puppy), if it's just him reaching maturity (which can come with behavior changes), or if there is an issue that needs to be further addressed.

Has anyone else gone through something similar??