If it hasn't been that way all of your life.. you need to get it checked on.. Some women have inverted nipples and that is ok if you are born that way... If it just started happening there is something going on.. the heaviness in the arm I'm not sure about... How old are you and have you had a mammogram? If not, you probably need to see a breast specialist and have one done.. Have you had any skin changes, nipple discharge, or feel any lumps in your breast? Hope all is well.

Ten to twenty percent of all women have inverted nipples.
But, if you're experiencing this for the first time and is only one-sided, you should be worry.
An inverted nipple can be a symptom of Breast Sheet Cancer ( Inflammatory Breast Cancer ).
Do you have redness, swelling, and warmth in the breast?
Does the skin of the breast appears pink, reddish purple, or bruised?
Is the skin like the skin of an orange?
Do you feel heaviness, burning, aching, increase in breast size, tenderness?
Can you check for swollen lymph nodes under your armpit or above the collarbone?
Inflammatory Breast Cancer is hard to detect in a mammogram.
Please, ask you doctor for biopsy!
Take care!
Marija

I went and had a mammagram & ultra sound done on my breast today they said mammagram looked fine not sure about the ultra sound if nothing is found in either should I still worry about the inverted nipple!