What Causes Excess Fatigue And Menstrual Pain Long After Having Endometriosis?

I am 33 have 3 kids and done lol I have had endometriosis for about 20yrs, have had surgery once in 1999 and again after the birth of our youngest daughter she was 2 so has been 3 yrs now and nothing has changed aside from no longer having my period and experiencing more pain n discomfort....and now new things my knees have been swollen for a year no and not due to injury, have been checked for blood clots and have none......I have pain during sex still, severe random pains in pelvic are all to.es of day all month long, feels like things pulling and tearing sometimes if I sit for a moment and stand, extreme fatigue ALWAYS, lower back pain that takes breath away....am tired of all of it and wish to feel better and be more active for my 3 children of whom I know am blessed to have after 2 miscarriages.........worried about whether or not things have progressed to something worse I know cancers can be closely associated with endometriosis and the lack of knowledge there used to be about my disease,endometriosis, has resulted in a lack in treatment and being taki. Serious for what I was concerned with and all the symtoms that I thi k are all related to my endometriosis.......will endometriosis really cause leg knee swelling and if so what does it mean??? Thankyou---K-Parker