My dog has a lump near her leg. It is under the skin. It is not bleed or like a sore, it is just a lump. It has been there for more than a year and it isn''t getting bigger or changing in colour but it is harder sometimes and other times softer. It is about half the size of a golf ball. She is energetic and not acting sick or anything. What could this lump be and what should we do?? It is the same colour as her skin and almost never red. She is about 7 years old