sudden painful lump under left arm

Hi all,

I woke up last night and realised my underarm was really sore, I thought my bra was pushing on it so I thought nothing of it- when i got up this morning and felt under my arm there is a lump :-( It has suddenly come i think. When i looked in the mirror i saw the underarm skin on both sides looks particularly..'scaley?' would be the only word i can think of. I'm just a bit scared! I am in the middle of endocrinology referrals to get my underactive thyroid treated. When I got the blood tests, my lymphocyte cell count was fractionally high but they told me it wasnt to worry about as it wasn't high enough to indicate anything bad, it was literally .2 over the threshold. Only other thing is that i am on citalopram for anxiety.

Can someone advise whether this sounds like a serious lump?

Thanks,

Clare :)