The Ultrasound is very useful too in distinguishing if the lump
is a cyst (fluid filled) or a solid lump
mind that most lumps found in
are benign in nature and you shouldn't panic.This lump could be a cyst or a fibroadenoma (both benign )that could cause the pain you are describing.Try to reduce caffeine intake (coffee, tea, soft drinks, chocolate) and also salt because it can help lessen the pain..
I hope that your upcoming tests will reveal nothing to be worried about.