Lately I have been feeling really sad and depressed and I don't know why. I really want to be happy and everything but no matter how hard I try I just, can't? This year I have had a lot of trouble with my 'friends' and I do feel like an outer and a pain to them all the time. I am always fighting with my boyfriend too, and I am feeling really stressed with my school work and fitting in socially. Does anyone know what this means? And what I should do about it?

High school or college?
Either way, a visit to the nurse or infirmary might be a first step. In college there are often peer groups too. Also if you are female, how are your periods and do you see any imbalance in cycles? Are you on birth control or do you take any other medicine, or any natural supplements? How is your physical health and your diet (college students can look healthy while eating really poorly, and it takes time to catch up)? How is your family with each other and with you? Please use Answer below if you wish to add more.

I'm in high school. Everything is fine with my periods and I'm not taking any of those things. I'm not a fit as I used to be and find when I'm bored or doing assignments that I eat really unhealthy. Everything is fine with the family

OK then, can your parents afford therapy? Even just 2 or 3 visits? Something is bothering you. When I was a teen it was my mother (who was miserable with her own life and took it out on everyone, not just me), but I didn't know why I was unhappy. When we are teens we often don't get the connection. I think most of us go through various emotional upheavals at that age, at least everyone I know.
Also, I don't think I was ever bored because I read books constantly. Is your boredom really depression and lack of interest in anything because of it? Have you no hopes and dreams (I know, that sounds corny)? What do you want to do with your life after high school?