Hello,
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The bleeding that you describe is not normal. Passing occasional small clots/tissues along with menstrual bleeding is considered to be normal. If they bigger and associated with heavy bleeding, then they could be abnormal and suggestive of underlying serious issues. Do not delay in visiting your doctor/gynecologist for further evaluation and assistance. You might require hormonal and blood work-up to rule out chances of hormonal derangements, bleeding problems, anemia, thyroid hormone dysfunction etc. An ultrasound scan done will help to rule out chances of endometrial hyperplasia, uterine/endometrial polyps, fibroids, adenomyosis, ovarian cysts, presence of retained products of conception (in case pregnancy is suspected) etc. Treatment as appropriate would be started based on your examination and investigation results. Look out for development of any other new symptoms. Be in regular monitoring and follow-up with your treating doctor/gynecologist and report any unusual symptoms immediately.
Take care.