Creams

So I had irration on my vagina from shaving, and I had heat rash on my legs. And my brother had heat rash on his ass before. And used my cream, if I use it after, he used it and let's say he double dipped, and if he has hpv, or gential warts or trich, or herpes or anything. Could if be passed on my sharing the diaper rash cream?