I had these horrible problems in college. I would have a node get swollen and continue to get big until I had to go have it lanced at the hospital. This would happen on and off to both armpits. Couldn't even put my arm to my side. After several times, they put me on a preventative antibiotic which stopped it altogether. The weird thing is that they sent a culture in and it stemmed from my pancreas I believe. not to scare you :0 I'm fine now..
my armpits always hurt me several days before i get sick.
there are lymph nodes in your armpits...maybe you are getting sick or have some sort of infection that has been caught in your lymph node. that is what people refer to when they say that their "glands are swollen." have you noticed anything similar on the back of your neck or in the other armpit? i am not a doctor, but i know that they tend to swell for me when i am getting sick. i agree with the above poster, definitely have a doctor check it out to put your mind at ease and make sure it isn't something more serious.
best of luck,
LS
Go to the doctor to find out what it is, and what to do about it.
Seriously, none of us are doctors, and we can't see it from here. You can get some guesses online, or find out for sure by seeing a doctor in person. If you are going to say you have no health insurance, try an urgent care center or local health clinic.