What Causes Severe Menstrual Cramps And Pain In Legs?

Hi I suffer from really painful menses. They are very heavy and have a lot of blood clots. My legs and lower stomach hutt so much that I have to bed rest for aleast 3 days.

I have been checked by a gyn but eveyrhing was clear.. They checked for fibroids and endormetrosis.

I am 24 yrs old, weighing 7 stones.