There are at least 2 more possible reasons for the symtoms you describe: trichomoniasis (in which case both you and your sex partners must be treated with antibiotics) OR allergies. The allergies can be to the kind of tampon you're using (scented/ bleached cotton), to any lubricants you may be using during intercourse (including the lube on the condom, if you use those), and even to your partner's semen and/or saliva.
Do NOT use Vagisil if you suspect BV!
Vagisil treats yeast infections. A yeast infection is an overgrowth of a fungus that can affect the skin (examples: Athlete’s Foot, nails (onychomycosis), mouth (thrush), digestive tract, esophagus, vagina (vulvovaginal candidiasis) and other parts of the body. Yeast infections occur most frequently in moist areas of the body. Although Candida albicans are the most frequent offenders, other types of yeasts (fungi) are known to cause infections. Diagnosis will vary depending upon the infection site and may include: observation, culturing a stool or mucous sample, or a scraping from the affected area or microscopic examination of a sample. Treatment is by topical or oral antifungal medications such as Vagisil.
On the other hand, BV is believed to be caused by bacteria. BV is treated with a course of Flagyl or Metronidazole pills (or Metrogel cream) - which are oral or vaginal antibiotics (anti-bacterial drugs).
Women with BV may have an abnormal vaginal discharge with an unpleasant odor. Some women report a strong fish-like odor, especially after intercourse. Discharge, if present, is usually white or gray; it can be thin. Women with BV may also have burning during urination or itching around the outside of the vagina, or both. You may want to try a product like vagisil, if that doesnt clear up the problem you will need your family dr or ob/gyn for an accurate diagnosis.