Is it permissible to prohibit something in order to protect society from corruption without being certain of its prohibition? And what is the ruling on a Muslim girl publishing private details related to menstruation, and is that considered personal freedom?

It is not appropriate for a person to publish their private matters on public social media unless there is a need or a benefit, such as seeking advice or treatment. Publishing private matters is not considered forbidden unless it leads to corruption in society, like inciting desires. Merely mentioning the suffering from menstruation is not corrupting society, but publishing it publicly might contradict modesty, and it would have been more appropriate to discuss it in women's or medical forums. If the discussion aims to incite desire and draw men to details of intimate parts, then it is forbidden. One should be cautious of prohibiting something for which there is no evidence, as Allah Almighty said: ﴿Say, "My Lord has only forbidden immoralities - what is apparent of them and what is concealed - and sin, and oppression without right, and that you associate with Allah that for which He has not sent down authority, and that you say about Allah that which you do not know."﴾ Al-A'raf/33.