My Missy kitty

Question
I have a question on the behavior of my cat. She is between 5 and seven. Over the summer I bought a cockatiel and because of the bird's young age, I have been paying her more attention but about a month and a half ago, Missy (my cat)left me a "clue" to her lonliness in the basement so I have been paying attention to her more so so she doesn't feel alone but lately she has been whining at night loudly and the other night she came into my room and my sisters, which is not allowed.
What's wrong with my kitty? She is fed, loved, and her litterbox is clean.

Answer
Megan,

I am assuming Missy is spayed.

Also, it is not clear to me from your question whether her litter pan habits are back to normal?  So, I will assume they are.

Whenever you bring a new addition into the household, it turns the cat's world topsy turvy,  They are creatures of habit and do get used to a certain order of things. So, when you brought in the cockatiel and, for all intents and purposes paid more attention to the bird than the cat (a naturally human thing to do), Missy did take some exception to that.

I would give Missy some more time to get used to the fact that you have a bird to share your attention.  If you continue to lavish Missy with attention and, maybe, some extra treats, she should settle down.  There is no gurantee that things will go back to what they were, but you need to realize that cats do and will get jealous.

Best regards... Norm.