Only time I seen digi's go brown is when they dont get enough light like falling in a cave or something. I have had incredible Digi growth and I attribute that to high lighting. Move it to a spot where you have increased light and see if it improves. Also as a safe guard you can dip it in bayer advanced and make sure you dont have any nudis snacking on it. Investigate your dip and see if you have any white fluffy things in it.