There is no such thing as medical grade boric acid. The chemical itself doesn't change just the manufacturer. Douching is not recommended anymore and can increase occurrences of bacterial vaginosis. Most women notice the smell after sex or after a period more because of the way the bacteria grows. The bacterial growth tends be more prolific deeper inside the vagina. Sexual intercourse pulls out these fluids and the smell is noticed more. It has nothing to do with sperm being introduced into the vagina.