Thanks so much for your reply and crossing of fingers - everyone who meets this little darling falls in love with her and I hope more than anything we can fix her!
She does not go outside but there are two other cats and a dog that do go in and out that could have transferred a tick to her. The outdoor animals all get treated with Revolution but Bella never has as she was sickly, young, and never went outside so I'm sure my friend just never thought of it. Now that you mention the tick-related illnesses, those do make sense and Lyme fits just about all of her symptoms - I just never thought of it because she doesn't go outside! I can't believe I didn't think of this! I don't want to get my hopes up too much but
you revealed the answer!!!