39 been referred to breast clinic! Freaking out

Hello I am new here, I have been reading some posts trying to get some answers or reassurance but  I felt perhaps I should post myself. 
im 39 and recently I had some breast pain like shooting pains from the top to bottom these were totally out of the blue. I started to feel the breast & I thought I felt a small lumpy area but since have not been able to find it again. 
I made app with GP who I saw about 10 days ago. She had a feel and said she agrees with me that no definitive lump could be felt but that the breast did feel lumpy. She said she would refer me to the breast clinic. The app has been made at the suspected cancer clinic and of course as soon as I saw suspected cancer on the app letter I have been in absolute melt down. 
I am terrified of the breast clinic appointment. I have to go on my own bcos of covid rules. What should I expect at the appointment? Mind has gone to all sorts of places this past week. Any advice would be massively welcomed. Thank you x