Hi Pippy. One explanation for the small dots is that they may be micro calcifications. Calcifications are common when women get older. Most times micro calcifications are non cancerous, but some women with with early breast cancer have mirco calcifications usually with other diagnostic findings such as a mass on the ultrasound and/or mammogram. This is what happened in my case. Your GP probably wants to be thorough and determine what type of calcifications they are.
Good luck with it
Nadi