Start off by stop using marketed products that you buy at the store. Antiperspirants have aluminum that clogs your pores, harsh chemicals, deodorants are just frankenperfumes that cover the smell and makes it worse. Petroleum jelly is made from "motor oil" and shouldn't be on your skin.
Try extra virgin coconut oil - it's antibacterial anti-fungal completely natural and smells good.
The vinegar sounds ok.
Thai mineral salt deodorant works very well to stop odor but it might sting if your skin is rashed.
As the previous poster stated you might want to get tested for skin problems or std's. There is an std forum here...