Suspected Endometriosis

[Peppette]

I've been having increasingly painful and heavy periods ever since I had my eldest son at 24y (I am currently 29y) but the past 6-12months I've been having a strange kind of painful pressure in my pelvis area. I went to the doctor this morning about it because it was so painful I couldn't do anything and he said he suspects it's endometriosis or (if I'm lucky) muscle spasms from my period.

He prescribed me 9 weeks worth of the contraceptive pill to be taken in succession and then asked me to go back right before they run out to see if it helps with the pain. My understanding is that essentially they treat the symptoms to begin with and make a formal diagnosis/send for more in depth tests dependant upon how your body reacts to the different treatments.

I've ended up a bit confused because 99% of my pain is during my period but this pill will stop my period so how will I know if it helps? Or, if it is Endometriosis, am I likely to get the pain at the time of my period without the traditional bleed? I tried to ask the doctor but his answer didn't really match my question so I think he misunderstood. Can anyone help clear this up for me? TIA x