Your symptoms are suggestive of bacterial vaginosis. This is unlikely to be syphilis which does not cause smell. And a STD screening also had been negative for you.
Treatment of the bacterial vaginosis is cumbersome. Following are the treatment modalities;
1) Metronidazole (flagyl) and clindamycin have been the drugs of choice.
2) Azithromycin too is effective, especially if there is recurrence or persistence. Secnidazole, ornidazole and tinidazole are also used in the case of antibiotic resistance.
3) Antiseptics as vaginal suppositories;
c) dequalinium chloride,
d) polyhexamethylene biguanide,
e) povidone iodine
f) hydrogen peroxide
5) Stop douching or bubble bath, if you do.
6) Avoid liquid soaps and body wash.
Please feel free for your follow up questions.
I would be happy to assist you further, if you need any more information.
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