Armpit Lump and Night Sweats

Well....I found a pea sized lump in my armpit. It is not painful or soft or movable and it is not red. You cannot see it only feel it. I am a 49 year old female and I have been having severe night sweats for about 4 months...I will wake up and the bed is soaked and I must change the sheets. I have not had a period for over a year and occassionally will become hot for no reason...I am assuming these r hot flashes? But the lump and the night sweats has me concerned. I have other issues and do not know if they are related. I am afraid I have Lymphoma or another form of cancer...any other symptoms I should be looking for? Thanks for any input
Robin