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My Chihuahua doesn't like the new puppy. He's been being aggressive, please help!

 we just got a new Chihuahua puppy ( a little girl) yesterday. She is spastic and literally the definition of hyperactive. we also have another Chihuahua, my 2 1/2 year old boy, who had taken a very big liking to me the day I got him. every thing was fine yesterday, he sniffed the pup and even licked her face a couple times. he growled a little when she played roughly with his own two pups ( both boys), but that is all that happened.
until today:
I was trying to get the pup to go to the bathroom and she kept bounding all over the place, especially on me, but my boy didn't seem to like that at all. He was suddenly very aggressive and made many sharp movements as if he was going to bite the little pup ( he didn't).
Is he jealous? afraid I like the pup more? or is he just trying to be protective?

He sees the new pup as an outside and not part of the pack. If you have not asserted your dominance over the male and have allowed him to do as he wishes then he sees himself of the alpha dog. In which case he decides who is part of the pack and who isn't. You need to be the alpha dog and put him in his place. You need to demonstrate to him that this new puppy is part of the pack. That the puppy either sits on equal ground as him or below. You need to correct any and all actions you think are questionable with both dogs. They both need to understand who the boss is.