Lump under arm

A couple of days ago I felt pain under my arm.  Today I noticed there is a bump the size of a grape.  I called the doctor and they told me that since now it is red (possibly from my touching it trying to figure out what it is), it sounds like either a bite or a pimple so they would not see me.  I am very worried because this has never been there and it doesn't feel like either.

[CCF-RN,MSN-rf]

Dear Ark82:  It is not uncommon to have an ingrown hair or pimple under the arm.  Give this a week or so.  If it does not go away or if it gets larger, give your doctor another call.

[KZee]

I too have just noticed lump under arm, actually i had one about 3 weeks ago and it dissapeared after 1 week.  Now I have it back again and it's really sore, it's a bit red, but not itchy or anything.  Should I see a doctor?

[mkrsh]

A couple of months ago I noticed a lump under my left arm. It is just at the point of my arm meeting my armpit.It has since gotten bigger now about the size of a small walnut), and tender at times. Other times it almost feels itchy for lack of a better term. IF I hold my arm out in front of a mirror I can see it. If I grasp the skin on either side I can feel it. Is this an area that may be a node or might be breast cancer related? I am not sure as this isn't exactly in my arm pit. Please relay any information that may be helpful. Thank you.