I had a fever in the week following DS1 birth and it ended up being a kidney infection.
I had a kidney infection as well. OP, please make a doctor's appointment if you have a fever, the longer you let it go, the worse any possible infection becomes. My kidney infection started as a UTI that I was on antibiotics for, but it had spread to my bladder pre-doc's appt for the UTI, and they put me on an antibiotic that only treated UTIs and nothing higher up, and then a week later I developed a fever, went to the ER and now I've had to see an internist 3 times for treatment.
EDIT: And I don't mean to sound like a hypochondriac, I'd just hate to see the same thing happen to you that happened to me. In this case, I'd errr on the side of caution and get a doc's appt and see if they think it's necessary to do a UA. Just me though.