I lost my appetite but it's still easy to eat?

I'm 16 years old and for the past two weeks I've had no appetite. It's a weird feeling because I feel a tiny bit hungry every now and then, but it goes away in a matter of 5 minutes or less. I'm still motivated to eat, I don't have to force myself to and it's pretty easy to, I just don't feel hungry when I do it. I haven't lost any weight either in fact I've gained a pound. I can still eat normally but I just don't get hungry!!! And when I do feel hungry for 5 minutes or so, I eat and that just makes it go away faster. Anyone know what's going on???