Open Question: What is the cause of this?

It feels like my brain is switching down levels, in all aspects of my life. Like for instance, I use to have tons of creative ideas, but they just keep getting smaller and smaller. I used to love working out and all of a sudden now I barely have enough energy to go to school and come home. I used to love doing nice things for people, but it seems like I don't really care anymore. It also seems I'm starting to blush now for no reason. All of this just started for no reason before Spring Break and is going downhill fast. I'm 15 and it feels like I have no sex drive at all either, I don't know what the cause of this would be? thanks for the help