The question asked do not have details regarding any sexual activity / trauma / any recent infection of urinary track, but let me still try and answer the question as much as possible assuming some possibilities which will be as follow.
Forced sex / permitted violent sex, before the symptom were seen OR recent blunt injury
to the private part.
The black spot seems to be a clotted blood , where the injury is localized only to internal area where the spot is seen, and the clot blood will appear dark brown to black in color depending upon the days passed after the blunt trauma/injury occurred .
let me walk you through what i mean by blunt trauma and what occurs with in body,
BLUNT TRAUMA is an impact where no external cut are noticed and can lead to a collection of blood pooling inside the organ known as "hematoma", it may not be visible by naked eyes but may be hidden deeply ( the shock
wave can create an tiny blood vessels to rupture leading a loss on blood internally in the organ but the cover of the organ will mostly enclosed it so it will not come out but will stay their) eventually it will be healed by absorption and macrophages(blood cell) will engulf the hardened dark blood but will take a long time to regress.
In your case you are having the pain and swelling around the region,
Go to hospital and get it address, if the pain is extremely hard to bear, as there may be some kind of infective processes going on so it better to take medical help
rather then to wait for Monday appointment.