I have discovered a lump under my left armpit last Friday and since then it made a button on top of the lump and today(Thursday) the button burst itself, I tried squeezing it and white stuff with blood came out and now its hard but still big-ish and a struck of pain comes when I try to squeeze it more

Is it an ingrown hair or something more?

I've had an ingrown hair once but I somehow feel this is different 

Its been 7days already