Lump on female dogs vagina

Today when I returned from work, I noticed a lump on my 10-year-old female dog. Duringthe day, she has been licking herself frequently but is eating, drinking, and urinating normally. There were traces of blood where she lay, indicating she might have bled lightly. I've attached a photo. Although we have a vet appointment tomorrow, I'm quite worried. Has anyone encountered a similar lump? Any insights would be greatly appreciated. Thank you for your help.

Hello - I am concerned about this.  I wonder if this might be a prolapse of the womb or cervix (the entrance to the womb).  If so, the black tissue might suggest that the womb wall that has been consequently deprived of blood.  Other possibilities include an unexpected pup or placenta on the way out, or a tumour.  This may well be a emergency situation; please call your vet for triage.

Triage = the act of deciding how urgent a case is.

Please call your vet right away for triage.

Thank you very much for your answers, Maja was immediately examined by a vet, the tumor was removed, it was Sticker's tumor, we will also undergo sterilization in the coming weeks.