I noticed a painful lump in my armpit on tuesday.but now the lumps less painful. but today morning i felt dizzy and feverish and fatigued.

Boil vs infected cys: You probably have a boil vs an infected sebaceous cyst (infection of a gland producing oil for the skin). I would recommend warm compresses with epsom salt ex 30 min. 4 times a day to help drain it. If it doesnot go away within 1-2d., it will require incision and drainage by a physician.

OR: mono: Another possibility, common in folks your age, is infection with Epstein-Barr virus, the cause of infectious mononucleosis, especially if you also have a sore throat. As other doctors suggested, only an examination of YOU can distinguish among the many possibilities.