I know this is a very basic question but have you been getting 8 hours of sleep a night for the last week? This sounds a bit like something that I went through this year and I realized that I had been getting 6 hours or less of fretful sleep. What would happen is I would run on very little sleep but I'd feel okay in the morning so it became acceptable until I crashed after 4 or so nights and had one good sleep then I'd go right back at it again. Try to get 8 hours for a week even if you're feeling better. It helps balance things and your body processes emotions a lot easier too.
Other than that I agree with SC and Idealist, therapy is good. Also just spending quality time with your friends and maybe taking a little you time away from people in general. Go for walks, play computer games, read, take naps, whatever lets you be in a space quiet and on your own.
Hope this helps and welcome to the forum!