I would definitely go get the lump checked out asap! But I have to say, my friend discovered a lump as well about 2 years ago. She was too afraid to go to the dr.'s no matter how much I told her she needed to go. Even if we offered to go with her....so long story short.
When she got pregnant and started going to the dr.'s, she obviously told the dr. about the lump (believe me, it was there. she made me feel it once!) and it was gone! The dr. said there was nothing there and she never actually got an answer about what it was. But knowing all the stress she went through....just go to the doctors and get it checked out. If it's something serious, at least they can start treating it asap. And if it's nothing to worry about....at least you know and won't have to worry about it anymore!