I think that the few days period between Pesach Sheni which is on the 14th of Iyar, and Lag B’omer on the 18th of Iyar , are called the days of matmonim because Hashem’s Glory, Tiferes, is hidden. Our goal is to bring this hidden Aura and Light of Hashem out into this world through our mitzvos and maasim tovim.