My 4 year old daughter dry heaves and is sometimes sick every time she's upset or crying, is this attention seeking or could it be a serious matter?

Likely behhavioral: A kid may vomit, soil his/her pants, bang his/her head, etc. , if they have not properly transitioned into appropriate methods of reasoning when they develop useful language. Usually triggered when frustrated, mad or not getting their way, this is a behavioral disturbance that may require the help of a therapist to get back on track.