Dr. found lump

nstrange

i first noticed my left arm holding fluid about a month ago. after couple test ruled out anything wrong in my arm. i noticed about 3 weeks ago that my left breast had gotten smaller than my right. i thought i felt a lump but was not really sure. I waited for my follow up appointment today and my primary dr. confirmed a lump, but isnt sure if it is anything or not and is sending me for a mammogram and probably ultra sound and referred me to my ob to go over results. i am in the waiting game now to have my test done. i am 30yrs old. i have 2 children. i had an iud for 8yrs i had it removed last october by scope. i had been regular since then up until now. i am 27 days late but had light color tonight so hoping im starting. my husband had vasectomy so i know that im not pregnant. what is going on with my body?!