I dont care about anything anymore?

Its just I never care about anything anymore! I use to get straight A's sometimes a B here and there and I would cry if I got B's (lmfao) . I got my report card a few days ago and I did horrible since I just didnt care about my homework and put like no amount of effort into schoolwork and I just didnt care about my report card And when my mom and dad were spazing I thought it was funny. Whenever they spas I think its funny :p... I dont care about my friends I dont care about guys that I use to like, I dont care about my future, my goals my nothing, I feel really ugly lately and really tired and my heads so dizzy and I have major headaches plus my stomach hurts so badly everytime I eat that sometimes I cant even move. And I just feel so drained and tired and like I really dont give a crap about anything anymore and I just hurt all the time. help?