I agree with who-dis. You should see a doctor. It may be nothing, but it's better to be safe than sorry. Hope your boob feels better.
I would take this seriously. There is a kind of breast cancer that appears on the breast as a sore or bug bite. I do not want to alarm you or worry you. I would call your doctor today. It could be nothing, but the peace of mind that comes with it, as you will see, is WORTH THE PHONE CALL AND VISIT.
I have also heard of the breast cancer....this is not to scare you, but I would go to the doctor to be safe like the above poster said. It is called Inflammatory breast cancer. I have posted the website. If you want to check it out there is a video link underneath Video Komo 4 News. It is the first one called The silent killer. It shows acutally photos of what it looks like on a womans breast...like a bug bite. This can help you also to determine what you mite have on your breast. Again, I am not trying to scare the **** out of you, but it is better to be safe than sorry! Good luck!
http://www.komotv.com/ibc/