The first thing that you need to do is set up an examination appointment. It would be impossible for anyone over the internet to know what the real problem is. A doctor needs to examine the lump and perhaps do some testing.Most painful lumps are rarely associated with breast cancer,particularly at your very young age.
there are many causes of breast lumps. Some of these causes are harmless, while others can be painful and worrisome.Causes of painful breast lumps could include infections, cysts and other non-cancerous growths.
Please see your doctor.If you have an infection it should be treated with medication.
any lump in breast should be taken seriously, you dont need to panic but please get it checked by a gp or scan. most of the times its just fat deposit but you dont know until you had it scanned.