What's This!?

Okay - I am quite embarrassed to ask this but I will. My armpit has this little lump and I know for sure its not anything serious.

I think.

It may be just an acne or an ingrown hair. I think the latter - but its really painful to touch. Its a bit red and every time I try to squeeze it; it hurts!

Anybody have the same problem? How can I get rid of this ingrown hair. Its too painful to prick!