School and mental health

This year has been the worst so far. School and my mental health has been the worst. And they kind of go together. When i feel bad i can't get myself to do the work and then I don't get a good grade and that makes me feel even worse. And it has been like thar for a while,  until two weeks ago. I suddenly got the motivation and actually started to do the work, I got good scores on the tests and I felt more happier. And then it ALL went away a couple of days ago. Now I feel like crap and I don't know what to do. I had two tests today and they both went bad but luckily the first doesn't matter that much and I get to re do the other one in two weeks. Some would say that I have nothing to complain about but it is hard because I also have a lot of other things in my life. It's hard to be with friends and family, do all the chores, hang out with friends, take care of yourself, go on all activities/the gym. It's a lot sometimes and then you need to drop something or move plans and in the end it's always going to be too much. And when that happens I usually isolate myself from people and just lock myself in my room. I get cold to people and sometimes I just take it all out on them. Which I don't mean but I can't really do anything to stop myself and it's really hard to explain all this sometimes. Sometimes I just wish that I was happier and had more enrgy to put into life.