I have a painful purple bump the size of a very large pimple in my ear near the cartilage. what could this possibly be?

Painful=infection: it may have started a an obstructed pore/follicle now infected...skin discoloration and painful lesion may be indicative of MRSA cellulitis/abscess formation...get seen by doctor the may decide to open it drain it and culture the discharge to identify the bacteria...good luck

Exactly where?: Earlobe??? Probably inflamed acne. If it drains it will feel better and heal faster + better. Sometimes an injection of triamcinolone is helpful. A dermatologist will help you. Older people can get a painful pimple out over the cartilage called chondrodermatitis nodularis helices.