First of all, welcome to this site. I know how frightened you probably are. What you need to do is take a deep breath, try to relax, and call a doctor for an examination. Then, when you have done that, you should know that you have done the right thing by being concerned. Many men ignore bumps. You are wise to ask for more information.
Now, just so you know, a lump can be a lot of things, a bone spur, an accumulation of fluid, a cyst, an overgrowth of old scar tissue, and other things, besides cancer. So, the hardest thing will be waiting for the test results. But, remember, these types of life situations can bring out a side in you that you never realized you had. Your inner strength. You can use it to get through this hard time. There are men all over the world who have shared this situation. You are NOT alone in this.
I have done a search on male breast cancer, and here is the site for you to get some information. Read it, and then you can decide on some questions to ask the doctor during your appointment. Our thoughts will be with you.
http://www.medicinenet.com/male_breast_cancer/
article.htm 
