Scrotum sac

yuck.

It's a infection of some kind. You need to see a doctor.

You should never be embarassed to go to the doctor unless its a superchick lolll

Cut it off

doctor. prob an infection if u washed and its still all gross then its most likely an infectionn :/

and i am too lazy to read all tht ^ but its prob ritee

Vomit smells like vomit because there are certain bacteria that live in everyone's guts that produce that particular odor.
Obviously, these are rather hardy little buggers.
Some get expelled from the guts when, as you mentioned, you vomit or, as it turns out, when you don't.
The point where these unvomited bacteria is expelled is, guess what, pretty darn close to the scrotum -- and most of us keep our scrotums confined in a warm, moist, dark place that is just perfect for breeding bacteria.
Scrubbing and using harsh chemicals isn't likely to help, and it is more likely to make matters worse by damaging the skin.
A normal metabolism wouldn't even allow these kinds of bugs to excessively multiply on the skin, which suggests you may have a problem.
Diabetes, for example, is one sort of metabolic disorder that might allow growth of undesireable bacteria on the skin.
Go see a doctor. There is nothing possibly wrong with you that (s)he hasn't seen or studied in great detail (man, they stick their finger in your anus to check your prostate!). What's more, (S)he can check for an underlying disorder that potentially could be much more serious than an unpleasant odor.