The smell from crack is a sweet faint chemical smell & doesn't linger very long. You possibly might smell amonia if they are cooking large quantites but it doesn't take long to cook, and the smell disappates very quickly. Just talking about it makes me feel ill.
Call the police if you think people are cooking meth next to you. It is very dangerous.
Whatever it is, I wouldn't suggest you let your kid breath it in. It can't be good for them.
I repeat, if you are worried, call the police. Sounds like a dangerous situation.