Endometriosis, late period and coccyx pain

Asking if anyone else has experienced this… I was diagnosed with endo a few years ago, it’s painful but manageable. The past 2 months however I have had excruciating coccyx pain to the point I can’t walk that is only there just before and whilst on my period, it’s fine the rest of the month. However my period is late now which is very unlike me , I’m not pregnant and I am wondering if this could be linked to the coccyx pain? Any thoughts? I am going to speak to doctor on Monday too.