Lump in breast?

Sabrina
Hello ladies.
I went to the doctor about two weeks ago for a lump in my breast. Got a mammogram and an ultrasound but the doctor said it wasn't cancer, but didn't tell me what the lump was.
It's now growing. Before I couldn't feel it when I was standing up and now when I stand up I barely have to press in to feel it and it looks like it will be protruding soon.
Would you suggest I go get a second opinion or leave it alone and stop worrying?