Pls help dark spot appeared on my lip overnight

I’m really worried because I made out w someone I had never been w before yesterday and now today I have a dark spot on my lip? If you can’t see what I’m talking about it’s on the upper right of my lip in this picture. It’s more noticeable in person and it was not there yesterday. Could this be an std? Cancer? Just a sun spot? Note- I also smoke and I smoked a blunt yesterday could I have just burnt my lip or something? Ive never had this before I’d appreciate if someone could help me I’m very worried ☹️