Hello again, Mike.
I was hoping to get some additional information from you before answering, but I will send my answer now, and if you have any additional questions, just let me know.
Kira's symptoms are very generalized and can indicate various types of underlying medical conditions. If she spends any time outside, she could have gotten into a non-food item like some old food, a toxic plant or flower, etc. and this is causing her lethargy, reclusiveness, plus, adversely affecting her appetite. She could have ingested something she shouldn't have, inside the house, as well.
Is it possible that she found and ate a dropped tablet of human medication, food she shouldn't have had or any non-food item and you weren't aware of it?
It's possible that she has developed a respiratory or cardiac condition that is causing her increasing lethargy or she could have a bacterial or viral infection in her system.
Even if she is an indoor-only cat, she could have been stung or bitten by an insect or venomous spider inside or outdoors.
She sounds young for this, but a mini-stroke or brain tumor cannot be ruled out until she's seen by the vet.
Not eating or drinking at all or properly for even a short period of time, can cause dehydration and also cause a serious liver condition, so because this has been going on for a little over a week, it would be advisable to have her evaluated in person by her vet or an ER vet, to find the reason for her symptoms and have her treated, so she can start feeling better.
I hope all will be well with your Kira! Please let me know how she's doing and what the vet's findings are. Thanks!
Please be so kind as to rate my answer with positive feedback from the ratings box at the top of your page; that is the only way I receive recognition from the website for my effort and assistance. Thank you very much!
Providing a positive rating will not end our conversation, should you need me for any follow-up. Simply click 'Reply to Expert' for clarification and/or additional information, if needed, at no additional cost.
Please don't hesitate to request me by name, for any future questions; just type: "For Cher Only" to begin your post.
Bonuses, although never expected, are always welcomed, for a job well done!