Tonight when I looked in on my birds before bed my yellow male gouldian finch was twitching. Like his whole body every 6 seconds or so. I've never seen this before and I'm freaking out a little

He's currently molting, he is not puffy and he is at the top of the cage perched on a branch.
I gave them nv powder just now, maybe that will help. The only other weird thing, was he was being slightly aggressive to my other male gouldian earlier tonight when i changed out their seed, and normally he is the friendliest one with all of them. And the other weird thing, my two societies aren't sleeping on the same branch. The yellow male gouldian is next to the female society. And my male society is on a different branch. They are never separated to sleep. The female society is sleeping hunched over a little, which is weird for her as well.
If you have any suggestions please let me know, I don't want to lose any of them

I have 4 gouldians and 2 societies in the cage. My guess is my yellow male is about 1 and a half, he is definitely over a year.
thank you all!