Am I depressed ? Should I seek medical help? I'm 16.?

I'm at a summer program and am so unhappy. It is the fourth day. I have some friends so Im not alone or anything. I can't eat I'm never hungry. I force myself to eat once or twice a day. I have gotten noticeably skinnier in just this time. All I want to do is sleep. I have skipped activities because I have no desire to do them. I am homesick. I want to go home. I don't care about looking nice or anything. Everyone else dresses up and I wear sweats no makeup no hair done. Literatly every second I am holding back tears. All I want to do is lay in bed. I hardly go to the bathroom as in poop. Every 3 or 4 days. I'm 16 and a girl. Pls help thx