I noticed two days ago that I had a small knot in my armpit and that it was pretty painful. Over the past two days it has grown and it has become more painful and to the point that it hurts to lift my arm up. Also, my arm seems to ache. There is no visible spot on the skin, however you can see that the area is swollen. Is there anything I can do at home to relieve the pain, or is it severe enough that I need to visit the doctor?