I am always sick and I don't know why help???!!?

About 15 minutes ago I posted this question but I thought I'd ask again but with more info So every week I am sick for maybe about 3-5 days I stay inside all day Really all I do is drink green tea and eat chips and bagels and grapefruits I also play on the computer all day and sleep and read I don't really have friends to go anywhere with?? Im gona for like 2 days to go spend time with my only firend who is like 45 minutes away and usually I get headaches from it all and I get sick at her house to. I wanted a list of maybe healthy small snacks and meals that are simple and maybe drinks and a exercise??im 12 lolll