I have a dull pain (4 out of 10) in my armpit that has been coming and going for the past several months now. It never lasts for more than a week, usually only a few days. I have never noticed a pattern in when it comes back, sometimes it will go away for a month, other times only a week or so. A few times I have noticed a small lump there, no larger than a pea though. It is only on my right side. I am female, and 20 years old. Can you help me?