Clear, Oily Discharge With White Liquid From Breast. Advised To Get A Prolactic. Suggestions?

im 24 yrs and have a 2 yr son. ive breast fed for 4 months then stopped due to work. occasionally my left breast gets sore and feels like i need to release pressure, like pumping. but i havent breast fed for well over a year and a half. recently i tried to gently squeeze my breast down to my nipple and clear, oily liquid came out along with small white liquid. my breast no longer feels pressure, but am concerned. i have had a ultrasound and a mamo done but my obgyn said its nothing. she mentioned to get a prolactic? lab done, but didnt.