Please help!! Painfull swollen bump under armpit...?

Let me start off by saying that "yes" I have an appointment with my doctor, but not for another 7 days. I have tried to research the symptoms but it leads me in so many directions from abcess, lymph nodes, to clogged pores perhaps from deodarant. I do use an anti-perspirant but have always and its never been an issue. How do I know whether its the lymph nodes or not? Or whether its one of the others I mentioned. I am a male, 35 years old, height weight proportionate, been under immense stress that started in January and has gotten worse. I don't have a sore throat (read this somewhere)...I am and have been very fatigued (but I believe from stress...but could be wrong)....no energy. May have been coincidental but when this painfull (about size of a quarter...one little smaller than a dime) I would stand up at times and get very dizzy. Much like when you get up to fast and for a few seconds its hard to see...almost want to fall. From what I have read its probably not cancer (who knows). I haven't been drinking alcohol, don't do drugs, do smoke cigarettes (I know I shouln't be). If anybody knows of what this could be while waiting to see my doc I would greatly appreciate it. Its been an issue now for 2 days and has gotten worse and more painful. Is there a way to tell whether its a lymph node? Also read a little about chronic fatigue. Body aches a little as well. No earaches or cold symptoms other than being achey and fatigued. Been fatigued for a while but has gotten worse. Have not had regular sleep...sometimes I have sleep issues...especially due to stress. Thank you.