advice needed

so i have an 8 month old chihuahua/yorkie mix and for some reason in the last couple days she has become very possesive of my bedroom and bed when it comes to the other dog or cats she will literally charge at them growling and snarling until they leave my room this is a recent behaviou that just started after i got her spayed on wednesday she never did it before but i just want to nip it in the butt before it gets worse any tips