Sorry Amanda I've been late to replying to your post. Sorry to hear about the pain you are in. If you google Endometriosis you should be able to find some websites that will provide you with lots of info on the details of this disease. To sum it up, it is pretty much when the tissue that lines your uterus starts to grow outside of your uterus in your pelvic cavity. So as you can imagine when you get your period what is is like when you shed that stuff, it goes out of your body, but with endo that stuff is also being "shed" inside your pelvic cavity and its sticky so it attaches to other organs like you your uterine wall, ovaries, bowels, bladder, etc. It can even fuse some of these organs together or form cysts which you know about from your experience with them. I would see your doctor again or find a new one if you aren't happy with your current dr. With all the pain you are going through they might want to take a look at what is going on inside your body or maybe they have some suggestions on how to treat the pain.
In the meantime I would take ibuprofen for the pain if you are able to and use heating pads or take hot baths to help relax those muscles and ease the discomfort you are feeling. Also google diets for endo. I haven't tried one myself but have heard many other women finding success with changing their diet. I know I get lots of bowel pain and IBS issues due to endo so cutting out some foods or eating less of certain foods like dairy has helped me a little.
Let me know if you have any other questions and keep us updated on how you are doing