This never happened before.... Help

So today i woke up with the urge as if I'd peed in my sleep, i got to the bathroom and i was bleeding old ish looking blood. Like blownish almost.... I freaked out because ive already had my period and that's never happened before. I went to google and idk what exactly to believe tbh it says that it could be early miscarriage which happened 1-2 weeks after fertilization. But is it possible for somethings like that to happened. Last time i had sex was literally a week and 1 day ago on Friday the 15 and yes it was unprotected, and today is Saturday 23. So does anyone know if that's possible, cause i mean i dont think that u can "almost" be pregnant with in a week and I thought a real miscarriage happened within 12 weeks. Like im serious really confuse...has anyone gone through this? Can anyone clarify? 
Btw just to make it clear im 19 and my fiancé is 23 so dont pls dont judge me about the "unprotected part" 😅😅❤️