Help me internet, you are my only hope.

[lunasee]

So I'm concerned about my cat, Una. She's ten months old. Yesterday, she was in the bathroom with me while I was doing my hair, and all of a sudden she got really spooked out. She was in one corner and backed up really fast into the other side. I opened the door for her and she bolted out of there. The whole night, she was acting very skiddish about everything. She recognizes us but isn't as sweet as she usually is. She's very aprehensive about everything, and is walking very slow and VERY low to the ground. She loves sitting in the window but is terrified of it now. She doesn't enjoy playing with mice, and won't fetch. This morning, she went to go into the bathroom (very slow again) but got really freaked out by it and ran the other way, which is weird because she LOVES to be in the bathroom. The woman who was boarding the kittens before we got her kept them in the bathroom, so I think it's a safe place for her. She also loves running water and would shower with me. And her favorite past time is pulling all the TP off the roll. Now she won't go near it.

I'm worried that something went off in her brain and maybe it's a disease or something? (I found a website where someone had a similar situation and it was some brain disease). Has anyone ever experienced anything like this? I'm also really sad because she was so sassy and loving, and is a completely different cat now.

Edited to add, she will play fetch, but only upstairs. She is still scared of the downstairs. After doing some investigation, I think she saw her reflection in the metal garbage can, and thinks we have some other animal here. Maybe she is just walking around looking for it?

We are taking her to the vet this week, but hopefully she gets over whatever it is before that. Thanks for any suggestions or advice you may have.