It could be fluid ..... Seroma maybe that's what breast fluid is called ....I had a double mast last year and both my breast areas would fill and become very uncomfortable ... And a breast care nurse would use a needle to draw the fluid out ... The fluid kept coming back for me for the next 4 mths !! ...the fluid is normal and it's the body s Way of healing itself .... But check with your breast care team .... Good luck with everything !!