I have a niece age 2. He can only say two words. Vomits most of the time, and when he shows his anger, he will force himself to vomit or bang his head. Poor eye contact.

That sounds like a mental issue more than a behavioral issue. Have they gotten her tested for this or are they living in the world of denial?
Child should be tested for autism

I have a niece age 2. He can only say two words. Vomits most of the time, and when he shows his anger, he will force himself to vomit or bang his head. Poor eye contact.
It sounds like he may have autistic tendencies, get him to the doctor and ask for a second opinion, good luck

Kind of confirms my worst fears.

Thanks for all the replies. I'll see what I can do.