Old zebra finch moving its head back in forth

[StodOne]

So I noticed my male zebra finch behaving strangely , sometimes he randomly starts moving his head to the right and then moves it back to original position and repeats it several times sort of like when someone is watching from a car things that pass by the car .
And then he started jumping on the perch in circles but it seems as though he had balance as he did not fall down or anything , i have noticed that he would do this from time to time so I decided it is best to ask for advice .
I dont know if he is just turning his head like that and jumping on purpose or does it have something to do with dizziness .
I did have a bell in his cage it was made out of metal as far as I can tell it does not contain lead copper or brass , im not sure about zinc dont really know how to tell it apart but it definitely is not heavy as lead or orange as copper .
His droppings seem fine brownish with minimal white and normal ammount of urine from what I can tell .
He chirps constantly although i have noticed him loosing some of his feathers near the neck but i believe he is just molting .
He does like to groom himself a lot and scratch his head from time to time, and right now when i look at him he seems fine and is even taking a bath ^_^ , I dont know if it is possible for a bird to basically make itself dizzy when scratching or grooming hard because i notice him doing that after he has done grooming.
Another question I have noticed that one bag of seeds seem to contain some kind of webs and I believe it is due to moths , can moths be dangerous in any way to birds and should i be worried about moths trying to lay eggs on the birds feathers is it even possible?
And also some moths apeared in my bird room .
Anyways thats all , thanks for replies.