Sciatic endometriosis and retrograde menstruation

[Samita37]

Hi,

I am 37 years old, trying to get pregnant and in December 2020 I started to feel some pain in the pelvic area, my right hip, and right leg. It happens every month when I get my period and it lasts for some days. The doctors don’t know what it is and they say they don’t think I have endometriosis. I only had ultrasound to check my pelvic area, but I think that is not enough.

I found some information on Internet about a possible endometriosis that can cause this sciatic pain (sciatic endometriosis) and also something about retrograde menstruation. It seems that a retrograde menstruation can cause an endometriosis. Could you please talk about these two things? Is there any more information about it? Why does the retrograde menstruation happen? How can I know if this is what I have?
Is there another way to check a possible endometriosis or retrograde menstruation? I can tell that my periods are less intense since this problem started.

Thanks.