Telephone appointment with breast clinic after ‘ok’ ultrasound

Hi everyone, last month  I was referred to the breast clinic and I noticed nipple change, tenderness and thickening in one breast. At the assessment 3 separate people took a look and feel and were all intrigued by my unusual change to the nipple. I then had an ultrasound, they said the machine they was using was quite old and struggling as my breast was very dense so moved me to another room to use another ultrasound machine. She then called in a senior to take a look and she carried it out again they said they believed it was glandular tissue. I heard them use the word shadow a lot when talking to each other throughout the imaging. I was told all was ok and although unusual they was sure it was glandular tissue problems. I was given some cream for the nipple and told to keep an eye. 
since then I think the nipple is changing again and the thickness is worsening but I don’t know if this is all in my head. 

Today to recieved a letter to say I have a telephone appointment with a clinician from the breast clinic. I am really worried what could this be? Why would I need a telephone appointment so soon after.