Noticed this under my tooth...?

Hi I’m due to go back to the dentist and booking an appointment for two weeks time, but I was just wondering if anyone could help me out before then to see what this is... (photo link below) I’ve only recently noticed it it’s a dark spot under the gum below the tooth, I’m not sure what it is, I have poked at it and brushed but it’s not food it did bleed slightly so other half said it could be a blood vessel (bruised) but I’m more scared of it being a cavity... I’ve noticed it about a week ago now, and it’s worrying me slightly... I’ve had no other problems with my teeth other than the one in front of it going dark inside which I think will need filling, and my one wisdom tooth has been growing through for four years and I’ve had two infections with that tooth as it’s still pushing through... Many thanks https://ibb.co/SXptVQP