Endometriosis can be a VERY painful condition in some people. I wish that Dr's would research more on understanding and treating this condition.
I know that some people find that if you totally cut out caffeine from your diet, it can help lessen painful menstrual cycles or just cramps etc.
Never heard of any natural remedies but the internet does have sites which mention special diets, not sure if any really work though.
Endometriosis UK
Surgery usually does help greatly, but again a some people find that it does not help them.
A temporary treatment is giving injections for up to 6 months to put the person in temporary menopause (usually before treatment).
Most Dr's say that becoming pregnant should either stabilise endometriosis or reduce it bcos it grows with every menstrual cycle and gets worse. Pregnancy doesn't cause any cycles giving u temporary relief (but goodness knows what happens afterwards!).
I think there is an endometriosis.org on the web that may have some helpful information...