My car has a rotten egg smell what you think is the cause of it?

rotten egg smell is related to the catalytic converter from wrong air fuel mix , you can have the code read at auto zoo and that may point you to the problem , remember they have sales clerks not technicians so you don't necessarily have to buy something they suggest , it's up to you . Why it would come from inside the car I don't know , I doubt you have a leaking exhaust .,

Gasoline with sulfur in it will do this.