Hi there, I am so sorry to hear of your pain. It is excruciating waiting for answers. I would think that the pain you are feeling is the endometrosis.
The liver can't feel pain though the sack around it can if the liver is enlarged. Is your liver enlarged? I stil think it is the former. I have known people with masses on their liver, they never felt a thing
Good luck to you, hang in there, Dee