Help! Black oozing growth!

My cat has had a black oozing scab-like growth on her back for about 2 years now. It doesn't seem painful for her, but it is constantly growing and the top scabby part will periodically fall off and reveal a black oozing center. She is a twelve year old black shorthair. I am just curious if anybody on here knows what it might be. She get very traumatized going to the vet, so I thought I would ask around here first. I attached pictures. Any help is appreciated!

She definitely needs to go to the vet!

I totally agree with talkingpeanut!  Your cat absolutely needs a vet.  There's no over-the-counter remedy for what your photos show.  I know you don't want to unduly traumatize her but the benefits of a proper diagnosis and treatment definitely outweigh any temporary trauma she may experience.  I hate to say it but that looks to be quite serious.    

Welcome to TCS 

As others have said, you need to take her to the veterinarian. I understand you don't want to cause her stress but this is a tumor and needs to be seen by a professional. It could be benign or it could be malignant, and if the latter, it should be removed as soon as possible, before it metastasizes. It could very well be something that's easy to treat, but without treatment could become very serious.

Good luck and please let us know what the vet said!