I've been doing what research I could into this, and here's what I've come up with:
Increased creatinine levels are usually the result of decreased kidney function. This is would most likely be due to the urinary tract infection. This can also be caused by damage due to high blood-pressure, diabetes or continued high fever. - Check for those.
http://www.netdoctor.co.uk/ate/liverandkidney/203337.htmlhttp://www.clinicalanswers.nhs.uk/index.cfm?question=567unfortunately this article sits behind a 'pay me!' wall, but from what I could gather from the google entry, raised creatinine levels are indicated for oestrogen treated women.
http://linkinghub.elsevier.com/retrieve/pii/S0022534705642644"The Journal of Urology : Etiological Role of Estrogen Status in ...There was no difference in other blood or urine parameters, although we noted marginally higher creatinine clearance in estrogen treated women. ...
linkinghub.elsevier.com/retrieve/pii/S0022534705642644"
Most of the other journal entries I could find are also behind 'pay me' walls, but it seems to indicate a strong correlation between pregnancy and raised creatinine levels. Are you on any progestins or progesterones?
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1631687The raised creatinine might be causing rather than be caused by the infection. I'm just guessing here though, since I know bugger-all about medicine.
I was hoping to find a bit more info, but the buggers all want membership! Maybe something in here does switch on a lightbulb though.

Sorry Ash, and I hope everything is okay!
Simone