What Causes Tender Breasts And Nipple Discharge?

i have the mirana, i have had it almost 2 yrs. last saturday i woke up nauseated and have been that way since now is 10 days. and sunday i woke up with my brests tender and monday my nipples hurt and when i squezzed them the sticky thick dis charge came from them as it did when i was preg with my 2 daughters. i have took 2 home preg test, showed neg, i went and had a blood test done today.. what do you think? could i really be preg with these symptoms? or is it just the mirana?