my dog mindy has developed a huge lump on her rear end by her tail. It must be the size of a baseball if not bigger. It's hard in some spots and squisy in others. I just noticed that she's bleeding from it now and I don't know what to do. She saw a vet when it was small and he said it must be a fatty tumor. Now a year later it has grown. They said they could operate but now that's it's so big is that possible?