I have endometriosis also and I found out that endo. is feed by estrogen, and it will even produce its own supply. I was determined to 'starve' the endo. of its food source. Through trial and error, I found that food helps or worsens it. No doctor has ever told me that diet can affect endometriosis.
I was already gluten free for Celiac Disease and one day was eating gluten free bread with flaxseed. I got very sick and couldn't understand why, since it was gluten free. I researched flax and at least 6 different websites said that flax topped the list of having a lot of natural estrogen (plant source estrogen) that our bodies can use. Those same articles also listed soy and gluten as 2nd and 3rd highest sources, respectively. But other sources of natural estrogen, not as high as flax, soy, or gluten, but enough to bother me was in mustard (the turmeric). I also found out that fresh strawberries bothered me, but strawberry jelly did not. I asked my Primary doctor, and she told me to cook all my fruits and veggies because they will all contain natural estrogen in varying amounts. Cooking them will kill it. Also chocolate, coffee and anything that contains caffine will cause inflammation and make the pain worse. Sugar also is an inflammatory food. So yes, food does matter. While diet may not help everyone, and I won't guarantee that it would help you, it did help me.
Start a journal of everything you do and see if you can find common ground.
Stress also will worsen pain.