Writing excuse letter due of cramps cause of menstruation?

Dear [Recipient],

I am writing to inform you that I will not be able to attend [event/meeting/class] on [date] due to severe menstrual cramps. I am experiencing intense pain and discomfort, and I believe it would be best for me to rest and take care of myself during this time.

I apologize for any inconvenience this may cause and I assure you that I will make every effort to catch up on any missed work or responsibilities as soon as possible. Thank you for your understanding and consideration.

Sincerely,
[Your Name]