Why am I feeling so empty and hurt these few weeks?

I'm a really happy and energetic dude but these past few weeks I've been feeling extremely empty, hurt, and sort of depressed even tho nothing is really wrong with me. I just feel secluded even tho I do have people around me but I just feel trapped and alone, and when I get a chance to conversate I back down wanting to be alone but when I'm alone I feel sad. I used to 3D model, play games, hang outside, and more but all these activities just feel like a burden to me and it doesn't give me the same enjoyment. I have to push myself to work on my modeling projects even tho I happily did them before. The feeling goes away sometimes but it hits back extremely hard and I don't know what I should do.