Don't panic. Just follow their directions for now. The ultrasound is showing those lumps you are feeling, They could be cysts or fibroids. They measure them and access what type see if you need a mammogram or fine needle biopsy etc. You need to wait to see what the doc says about those. Important is that you follow up with things, don't panic and leave things late. Take care and let us know how you go.
I too had dark spots on one of my mammograms. I had a second
mammogram and was told it was just dense tissue folding in on
itself and was nothing to worry about. Maybe if it had folded
out, I might have bigger breasts. Oh well! Good luck!