There is a Lymph node than runs into the earlobe, I had this problem a while back, but I left them and they went away, but every so often I can feel it coming back on my right ear.
I think what happens is that it becomes infected, and obviously it forms a hard, ball-like shape that Is sore to touch, just Google "lump ear lobe" for 100s of same questions.
edit, Googled it, some one wrote.
The most probable possibility is clogged sebaceous gland of the earlobe. It is not uncommon to have clogged sebaceous glands in the earlobe. They are a result of poor hygiene or some kind of an infection. Most people don’t even notice them, or notice them as small lumps in the earlobe, but some of them tend to get infected and they can grow to be very big and can become a great problem for the patient. They can hurt but they don’t have to, the pain usually appears when the lump starts pressing on some nerve ending in the earlobe. Trying to squeeze them out will only cause you more pain and can worsen the infection. The safest solution is to go to a plastic surgeon and have the lump removed. It may be the smartest thing to do because they could rule out the chances of some kind of a cancer, don’t worry the procedure isn’t painful and it shouldn’t take more than 15 minutes to do it.