I happened to keep a photo of my cherry tree last year about the same time. When I compared it with the one I got today. I found the true lump in the trunk grew larger significantly. See the last two photos.

When I take a closer look into the lump. I am very concerned. I saw a lot of ants coming in and out.



So, my question is, is this tree lump a normal one? Or is it an ants invasion? If it was truly caused by ants, what is the best solution to remove them without killing my beautiful cherry tree?
If these ants are just innocent travelers like all of us, and they have nothing to do with the tree lump, should I be concerned about the lump and do something about it? Could it be a tree cancer?
Please forgive my ignorance if I sounds like an idiot. As I said, I am a new gardener needs redemption.

Thanks,
H2O