Why did my dogs demeanor change?

Hey there, ok so I rescued a male dog(about a year old) several months ago from an abusive situation. He was very skittish, scared to eat or drink, & quick movements made him cower or hide. I've been able to work w/ him altho, he is a HORRIBLE barker when outside, he's quiet inside. He got used to me & the basic daily routine. the past several weeks his attitude & demeanor have changed. When its feeding time, he'll run in the room quickly & just start chomping away at the food then start eating the other 2s food. Even AFTER eating he'll sniff around like a starving dog, dig in the trash (even when empty), jumps on top of furniture sniffing around & has even jumped up on my tv stand & computer desk. If I pet or talk to one of the other dogs he'll put himself between us (not guarding stance but jealous), I had him broke of potting in the house but now even being outside most the day he comes in & urinates on things he didnt before yet familiar w/., he'll squeeze the others out of their spots then follow them around repeatedly doing so. Now again, he had stopped a few of these things but now hes really acting up. I realize hes trying to dominate the other boy but not my 3 legged male & to act so different so quickly has me upset. Ive rescued many abused animals, Ive seen alot of actions, yes, Vet veryfied him healthy, hes nuetured & due to his breed he is lean. And theres been no drastic changes to the dogs lives. Any suggestions or help?