Bump - no hair growth

About two months ago I felt a weird bump on the back of my puppy. Since her hair was really long I never noticed it before. Upon further inspection I noticed that the area looked like a black and blue. I put antibiotic cream on what I thought was a bruise. The black and blue went away but I still feel it bumpy and the area has no hair growth. Also the skin is a bit discolored. More of a pale white rather than a pink like the rest of her body. There are a few orangy dots. I recently got her a puppy cut because she was very beastly and now I can clearly see the circular area. below is a picture. Any ideas of what it could be? It has not grown at all. I am going to take her to get spayed soon and with my hectic travel schedule the last couple of weeks I have not had time to take her to the Vet but she has no pain, is eating well and as mentioned with the cream the bruising went away. Some additional background...I thought I was getting her from a breeder and later came to find out when she arrived very sick - kennel cough, ear mites and mlp of back leg that she really came from a puppymill. I am not really sure of her ages I was told she was suppose to be 15 weeks when I got her in November (birthday was suppose to be in August) but my Vet told me she was no more than 6-7 weeks at that time. Thanks for any ideas or suggestions.


Carolina