Yesterday (Thursday) I noticed my female cat using the litter tray a lot of
times (before this she used to go outside, only ever used the litter tray
on rare occasions, its just there for emergencies), each time she only had
a little piddle, at 5.50pm she went outside the litter tray and there was
blood in it, I immediatley took her the vet, he said it might be cystitis
and gave her 2 injections, one for to help the lining (I'm not quite sure
what he said because I was in a bit of a tivvy worrying about my cat) and
the other injection was antibiotics, her bladder size was normal not
swollen, he has given me antibiotic tablets to give her over the next six
days, first to start today Friday.  
What I would like to know, has anybody elses cat experienced this, how
long before it clears up? is there anything else I can do for her? How are
your cats now? Has it reocurred? The vet said stress may be a cause, but
she does not go out much, I have 3 other cats but they all get on
wonderfully.
Some of these questions I should have asked the vet (I know I can phone
the vet back if I am worried, but I would like to hear from somebody whos
cat has had this problem) but at the time the cat was stressed out with
the travelling in the car, being in the vets surgery etc., I just wanted
her to get seen to, get her medication and get her home asap were she
could feel relaxed and safe again.
I would appreciate any comments you may have.

Thanks in advance
Tina