Hey guys, I’m male and 19 years old

Hey guys, I’m male and 19 years old, quite skinny as-well. I’ve been skeptical about this strange mark on my back. I’m a bit of a worrier, so that doesn’t help. But it’s been there for a while now, from what i believe it’s roughly 3–6 months. Could anyone tell me if this is a stretch mark ? Or something different. I’m hoping that it’s just a stretch mark, but it’s only one line. Thank you everyone x