My 2 yr old daughter was pinching her breast today and white milky stuff came out. what should i do or should i be concerned?

Monitor closely: I would have her seen in the next few days or sooner if the area develops any swelling or redness.I can't explain the milky material unless there are some stray hormones around creating milk.(needs eval) however, any expression of material at that age can open lacteals & allow germs to enter the soft tissue & cause a breast infection that could scar the area & interfere with later breast growth.