"What are you doing?"
I know this is a year late, but if anyone else comes across this thread, "你做什么？" means "What do you do?" Very different from "What are you doing?" Although a Chinese speaker would not interpret "What do you do?" to mean "What is your job?" they would still understand it very literally.
The real alternative is “你在干什么？“ The new character is "gan4"
你在做怎么? nǐ zài zuò zěn me Vs. 你在做什么? nǐ zài zuò shénme - What's the difference?