I take the sennosides tab because i suffer from strong constipation , but during the period the bleeding is severe and contains a large piece of blood?

? Pelvic congestion: Given the chronic constipation you suffer from, or other problem, you need to see a gynecologist for evaluation, a pelvic ultrasound may be needed. The constipation though have several reasons, thyroid dysfunction can be a cause, also not drinking enough eater, keep yourself well hydrated till sorted out by your doctor, good luck