What Causes Frequent Vaginal Irritation And Discharge?

I am 39 and i weight 104lbs. I have had re-occurring bacteria infections in the past. i have not had sex in over a year and a half. since then i have been tested for all std's. I thought that I had bv due to sex so i stopped dating. Then i thought i had re-occurring bv because of my sex toys so i stop using them. Now, my bv would go away when i don't masturbate and when i do ( 3 weeks later) i would get immediate itching and yellow discharge the very next day. It is not due to poor hygiene or not using cotton undies and i don't douche. Its whenever I touch it any any way. why? Help me please!!!!