I've been discharging the last two weeks. and these past two days i've been having breast pain & nipple tenderness. what could it be ?

Unsure: If the discharge concerns you, see a gyn for eval. It could be that your discharge is due o infection or hormone changes. Hormone changes can also be the cause of your breast pain.

Many things: It could be many things. You could be pregnant, as it can cause discharge, breast and nipple pains, but it could be many other things too. Take a pregnancy test. If it persists, be seen for an exam.