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?

Your dog does something bad, hit it with a rolled up newspaper, that should do it for a chihuaha. Youve got to do what it takes to put the fear of God in that little sucker when it does something seriosly bad. Maybe you can do it with your tone of voice, i dunno. The dogs got to fold its ears back and slink and cower and put its tail between it's leg. Trembling is a good sign. People drive me nuts speaking english to their dog as if they understood to discipline them. Dogs understand true anger and physical violence. Better to beat the dog a few times than let it terrorize your home forever. It wont hold it against you like a child would, trust me. Beat the crap out of my dog to house break him. Did not take long. Same thing for agression at feeding time. You gotta lay down the law in a way they will understand. I know it's a chihuaha, that tough. Probably the rolled up newspaper route for such a small dog. You might try the water spray bottle or shock collar if you see that as more humane, I see that as taking longer/being more confusing to the dog/less humane.

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.