Lump on Back

Hi all, I know everyone here can understand the anxiety that comes over us when we find a new lump. A few days ago, my husband noticed a lump on my back. It's between the shoulder blades either on the spine or just to the right - that spot that I cannot reach or even see very well. He was able to take a picture so I could see it clearly. It looks like something almost the size of a baseball under the skin. There's no difference in the skin over it, normal color, no lesions or anything. Just looks like someone inserted a baseball under my skin. My sister gets fatty cysts on her back that sometimes need to be drained. This looks completely different.

Of course, with a history of breast cancer, I am scared that this could be a metastasis or a new cancer. Once you've been told before that it's cancer, it's not so easy to tell yourself it's probably not cancer. MO suggested I go through my family doctor first so I have an appointment Monday afternoon with her. In the meantime, I'm googling and worrying.

Anyone have experience with lumps like this? Or any expertise on how likely or unlikely that this could be a metastasis?

Thanks in advance.