Swelling and pain in armpit radiating to breast

[mahcre16]

A week ago I started to feel a stabbing pain in my armpit area. The next day the pain increased and I noticed some swelling. Now my armpit is noticeably larger than the other side and I can feel a hard oval shape in the middle of my armpit as well as sharp pain upon pressing in on the area on the side of my breast and armpit. It feels like I have a tennis ball under my arm and I have to hold my arm at an angle. The pain is worse in the mornings and when I raise my arm up to stretch, but never goes away completely. I don't have any cuts or nicks of any kind anywhere and I do not have a cold or any other illness. Wondering if this is something that needs immediate attention or if it is just a reaction to something that my body is fighting?

[concerned621]

Please get this checked. There are things like inflammatory breast cancer and it can affect the lymph nodes.  

[TRG2970]

In the arm pit there is a gland, this gland helps with sweat, and other things. Often times it can swell, and get some pain. If it continues i would suggest going to the doctor. It should go away within a couple days.