Help Help Plz Help! Sudden EXTREME Cat Agression

[heart433]

I just got back yesterday after a week away from my cats. That night my 6 year old unspayed female tabby, Yuki had an EXTREMELY AGGRESSIVE attack against my 8 year old spayed female tabby Tigger. THREE TIMES during the night she aggressively attacked her without provocation, following me screaming as I picked Tigger up in fear and put her behind a closed door. Tigger just had to be sitting still for her to leap at her screaming and flailing her claws.

She does not show any aggression towards our 1 year old kitten and play fights and washes her daily. And it was not a case of her thinking the kitten was in danger from Tigger.

She shows no aggression to me, in fact she has been unusually cuddly and seems to want to glue herself to my side. She used to be affectionate only when she was in heat.

This evening Yuki saw Tigger on the counter from a chair and tried to attack her screaming again. I picked Tigger up and shut her in my room. Yuki tried to follow me, howling lowly.

I'm terrified.

Tigger is not an aggressive cat, she cowared under my bed for most of the day. I worry about her stress about being attack negatively affecting her health. I don't want to give away Yuki because she is Molly's only active playmate, but if the chips are down I will choose Tigger.