I have small, squishy lumps under each arm...?

With the left underam, the lump was larger than the left and was very visible. It was very tender and painful. The pain was also on the outside of my left . This lump decreased in size greatly and is hardly visible but it still hurts. Then I noticed yesterday pain in my right undearm, and also a small squishy lump that has the same pain except with no pain on my right . What is this? Is this a sign of cancer?