Is it normal for your period to be clumpy thick and dark?
Yes, it's normal for your period to be clumpy and thick. Your
period isn't just blood but also uterine cells, uterine tissue,
discharge, and mucus, so on heavier days when there is more tissue
present it will look thicker and mucus can also thicken up flow
too. As long as you're using correct menstrual products to deal
with it you're fine, and as long as there is no bad odour
everything is healthy.