What Causes Foul Odor During Urination With Vaginal Itchiness?

I have had an odour when i've passed urine, for about 6 weeks. It is an unusual odour to me with a slightly sweet and unusuall smell. Occasionally I have an itchiness in the vaginal as well. I have been to my GP who did a swab of the vagina and also sent off a sample of urine. This came back as being satisfactory. Do you think I should have the tests repeated? I had breast cancer March 2010, and taking letrozole, calcichew, amitriptyline 10mg right now