Pea sized lump under armpit -painful!

[Kab13]

I have had on off aches and pains in my left armpit/breast for ages now and as it comes and goes I've been useless and not gone to the doctors. Everytime I say I will the pain goes and returns maybe a couple of weeks later.
Anyway, last night I woke up with a very sore armpit again, more so than usual. There's a pea sized "lump" but it doesn't feel like a ball you could just move about- more like a swelling.
Could this be my glands?

More than likely it's a blockage, some kind of cyst or big, deep spot. I used to get these hormonally. But you know you should get it checked out. As it's under your arm the doctor will feel for it, if she agrees it's there you'll be referred and they'll do an ultrasound on it.

I get this reasonably frequently. I assume it's hormonal becuase it always goes after a couple of days.