What Causes Fishy Vaginal Odor While Having Pcos?

hi am 29 years old i weigh 91kg and over the last ten years i have been battling with PCOS about three months back my doc made me do hsg x ray and since then almost everymonth i experience i terrible vaginal odour like fish or dead somthing and what i do is i buy candida medicine and insert then it's gone.i want to know is there somthing wrong with me cause i don't want to experience it again.my husband and i having been TTC for a year now