and tired?

why is it every time i have i feel get tired,and i dont feel high,i feel low,and i have mood swings, like before i have ill be confident and strong and funs but after i feel low and want to stay to my self,also why is it when i sleep some times i nut in my pants but its not really because a regurally nut is silver gray but this is clear but a lil bit sappy,it happens a lot and i cant control it, im 16 years old and want help