Wrinkle, help????

Hi, recently I developed a rather deep wrinkle on the left side of my face which runs from my nose to my mouth. Litterally, this just appeared one morning about a month ago... the evening before it was smooth as ever. Strangely, the right side of my face has no wrinkle whatsoever and is completely smooth. Is there something I did to cause this??? I have had a very very stressful past 2 years, and I always sleep on the left left side of my face, but why would this line only now appear??? It is really really stressing me out, I'm feeling like this is all my fault, I don't exercise really at all, and I know that helps for skin aging... but I'm 18 years old, I didn't know I could get a deep wrinkle like this at my age!?! This has me extremely stressed, to the point to where I am going to be getting it filled with juvederm immediently as it is a very deep and noticeable line, but can anyone please advise me how this has happened just all of a sudden??? or how I can prevent wrinkles from forming in the future??? Right now I am really really depressed, I thought skin wasn't supposed to start aging until the 30s and just knowing that I'm going to need to get this line injected for the rest of my life makes me extremely upset and down. Well, I guess I will end this here... please help though, the emotional/mental effect this is having on me is extreme, and I need answers for peace of mind. :(