Is this normal?

So I was diagnosed with endometriosis at a young age, if you have it you know the pain that can come with periods. Anyways, I was put on the pill and honestly had never even thought about my diagnoses for 8 years. Fast forward and me and my husband are trying to conceive now. I have been off the pill for about 8 months and while my periods have been “irregular” in cycle time AF has never been longer than 5 days. This time around I tested negative and AF came the next day, what was different was the intense pain I felt all day at work followed along with 12 days of bleeding. I am new to the area and the OB I called didnt have openings for weeks because of covid. I was curious if this could be my endometriosis coming back with a vengeance? Or if anyone else has experienced intense pain and bleeding with a period coming off birth control. The 7 periods before were normal in length.