I have a large oblong mass under my left armpit . It s is very painful along with joint pain , fever , fatigue , headache, chills . And night sweats , can t raise my arm above my head . The lump is about 4 to 5 inches in length . And hard . And warm to the touch . Started off as a little knot and over 2 days is the size of a small potato . Any info would be helpful