Cat problem

It seems as tho there is a certain liquid under my cats scruff or skin I can shake it and I can hear swishing and stuff but I’ve never had this cat have this problem before and Idk what it is it is only when I pull up on the scruff that the liquid moves freely

Hello!   I am positively confused by this because we used to occasionally inject free liquid (water) under cats' skins for various reasons to do with hydration, and it doesn't swish about or make a sound even in quite large amounts under the skin, but collects in very odd bubbles under the surface.  The practice has become less popular over the years and is thought to be painful.   I therefore wonder what it is that you are experiencing.  I have seen air / pus under the skin which can behave very oddly.  It may be worth calling the emergency vet for triage in case they would like to see you.

Do you have a picture?

(obvs attend to the patient first!)