Is it obligatory for a menstruating woman to conceal the matter of menstruation from the men among her family, especially during fasting, and is displaying it considered a lack of modesty, and does "If you are afflicted, then conceal yourselves" apply to menstruation, and is it an affliction?

There is no hadith with the wording: "If you are afflicted, conceal it." Menstruation is a natural matter, but societies consider a woman's disclosure of her menstruation to men in general, and even to her mahrams, to be a lack of modesty. This is called the modesty of propriety. Ali ibn Abi Talib, may Allah be pleased with him, was too shy to ask the Prophet, peace and blessings be upon him, about madhiy (pre-seminal fluid) due to the position of his daughter (Fatima) with him. A menstruating woman should not openly eat during the day in Ramadan; rather, she should do so discreetly, lest she be accused, because menstruation is a hidden excuse. The female Companions used to ask about matters of menstruation and janabah (ritual impurity) with extreme shyness, and had it not been for the need for knowledge, they would not have asked. Therefore, a woman should conceal her menstruation from her father, brother, and other similar mahrams out of propriety.