Dear Juliet6298: This is a breast cancer forum and this is our expertise. In terms of your lump and discomfort, this should be evaluated by your doctor. Regarding your other symptoms, a gynecologist could determine if you are menopausal. Your primary care doctor can evaluate your other problems.
Dear TATTYKATTY: There is no perfect test for detection of cancer. As such, it is theoretically possible to have negative breast imaging (through any method) and disease that has traveled outside the breast. This is not common but is possible.
Dear Lori2136: Without evaluation, it is impossible for us to speculate on what this may be. There are several possibilities. It is probably reasonable to see a specialist to see if further evaluation is warranted.