Any problems after stop breast feeding?

I have a baby and have breast fed him until he turns 2 years old. I would like to ask you about my breasts, since i stop brest feeding my son I can feel and touch the lumb inside and I think it still contains milk. It's usually painful before my period time. Could you please tell me how to avoid having lumb in breasts and how to get rid of milk inside them? Or is something wrong in my breasts?
Thank you in advance and I'm looking forward to hearing from you.