For diagnostic purposes and assuming money isn't tight, I'd suggest taking a Candida Questionnaire (link #1), and possibly a Candida PCR serum test (link #2, and both firms have websites) and Comprehensive Stool Analysis (link #3). Also read through possible causes in link #4. Also conduct a thorough search of "vaginal odor" on Google.com for possible non-Candida yeast related infections.