Painful lumps in the breasts are rarely associated with breast cancer.
It sounds pretty much that you have an infection. An abscess or a boil can be very painful.I would advise you to have it checked out by your doctor.
You will probably need to have it drained and treated with an antibiotic to clear it up.
Samantha,I had to add one more thing. I wonder if the discharge that you mentioned, comes from the lump itself or from the nipple.If it's from the nipple and comes out spontaneously it becomes more concerning but there's no reason to panic. While nipple discharge can be serious, in most cases, it's either normal or due to a minor condition.
Still,I urge you to contact your health care provider any time you notice breast discharge whether from the lump itself or from the nipple. Based upon your symptoms and the results of diagnostic tests, your doctor will decide on the best course of treatment.