Child hasnt had much of a appetite for a month & for the past month he has thrown up once a week but this week twice. any ideas what it could be?

Hard to speculate: Kids at that age go through spurts of growth followed by plateaus where they may not eat as much. Some kids puke for a variety of reasons, including illness, food reaction and others. If it bothers you a weight check and review with his doc may be worthwhile. Make a list of symptoms,issues & possible triggers & take it with you so you don't forget.