Endometriosis
How far does this go back? Probably when I was having my first period around the age of 13-14. I was very skinny and was bleeding so heavily that I became anaemic. The pain continued over the years with me taking full days off school due to the intensity of it. I never knew at the time that it was anything more than 'the usual' that women had to deal with. I thought it was the same for other girls, and while I knew the extent of the pain was so strong that it just didn't feel 'right', I put up with it. Every month I would, with no exaggeration, curl up into a ball and scream from the pain. I attended A&E throughout my teenage years and early 20's, because I would notice the pain localised to one side and it was unbearable. Each time I was sent away with paracetamol and told "I'm just not convinced it's appendicitis" - which obviously meant it was nothing. I think my parents would get frustrated with me as the nearest hospital wasn't close and every time I went, I would need one of them to give up their time to wait with me to see what the problem was.
It reached a point where the pain became a normal thing for me; it was just something I put up with. I would take a lot of painkillers and not worry.