What Causes Intermittent Pain In The Armpits?

I am a 38 year old female. Last week I had a category 4 mass (only .8cm) in my left breast biopsied--it was benign. I haven't gone back yet for a follow up so I don't know the specifics about what it is, etc. However, I have also been having an achy kind of pain off and on in my left armpit for months--sometimes it is sharp and radiates down to my elbow. I told the doctor this but she didn't seem too worried and the ultrasound tech didn't check my armpit either when I told her. Nor did the doctor recommend taking ultrasound pics of my right breast--should she have? Also, I am being followed for an ovarian cyst on my right ovary--gyn has told me that it is benign but she wants to follow to make sure it goes away. Also, I have notice that a couple of times a week I have been feeling really run down--need to come home and rest. I did have blood work done--CBC & hormone work up--all were normal. Any thoughts?