I did have a mammogram a year ago, due to a lump found in my left breast. I was 37 years old, which is younger than they plan on testing, but the lump was firm and stayed there for a several months.

The mammogram itself wasn't real painful. It wasn't very comfortable having my breasts squeezed by the machine taking the images, but it's pretty quick (like an x-ray) and harmless. The results of my mammo didn't show anything, but the lump did go away from all of the squeezing ~ we hypothesize that I'd produced milk in the glands & it stayed and hardened. The squeezing of my breast(s) crushed it, and it's gone.

That was my personal experience. Best wishes to you, hon!
Shez