Update-
Suey is home. She has a shaven neck from where they did the blood tests (they had to do it in the jugular, which horrified mum quite a bit). We will get the results on Thursday night or Friday. The vet is certain it is Cystisis, but ordered the tests to help put mum's mind at rest. She made the mistake of googling 'blood in cat urine'. Our advice- never do that. Suey is tired and seems pretty uncomfortable, but she is home. We intend on taking the very best care of her that we can. Thankyou for your purrs. Your support means a lot.
I have some news that has me and mum very worried. My little sister is sick.

On Monday night, she started visiting the litterbox as often as she could. All night mum could hear her climbing back in. She was exhausted by morning. She went to the vet on Tuesday. They gave her an anti inflammatory injection and an antibiotic injection, and diagnosed her with cystisis.

She seemed to be feeling a lot more comfortable last night, but just before 8pm she climbed in her box again and, without squatting like she normally does, urinated a large amount of very bloody urine. She cried, and broke mum's heart.

I watched her very closely until she went back into the vet. She has been there all day for observation and tests. They did a cytocentisis (sp?), and found her urine was off the chart with blood. The urine concentration and acidity was in the normal range though, which was good. Mum is going to go back in and see her in a couple of hours, when she should be able to bring her home. The vet wants to talk to mum about blood tests and ultrasounds.

I am very worried about my sister, and want her to come home and feel better.

We love you Suey.
P.S. Mum passed her test. Thankyou for your purrs.