Always tiered?

So for about the past two weeks I’ve been so tiered, all I want to do is sleep. The other day I went to sleep at 6 and didn’t wake up till about 8 in the morning. I have little to no energy for anything, it’s getting to the point where sometimes I don’t wanna eat I’m so tiered. I’m 16 so it’s kinda worrying me. And when I take a shower by the end of it I get dizzy spells and get really hot, and almost throw up because of it. I’ve made sure not to use hot water but idk what could be causing this.