I have a tiny lump under my arm HELP?!

I have a tiny lump under my arm HELP?

im writing this for someone elese who is female and this is her problem

about 2 days ago i noticed a small lump under my arm pit (about 1inch in with and length ) it really hurts when i touch it since it started it has slightly grown

and yesterday i started to feel unwell and now have a cold (i don't know if this is linked but i just thorugt i better include this information)

i am going to go to the doctor but was wondering if anyone may know the cause to put my mind at ease

There are several things it could be but is probably a swollen lymph node. These nodes become acutely swollen during infections. Tell her to keep an eye on it and it will probably get better in a couple of days. Of course, a doctor's evaluation is a good approach.