I have given these comments alot of thought. At the risk of sounding like an alarmist- I think its time for an exam. I also had severe endometriosis- scheduled finally jan 3rd for a hysterectomy after two failed procedures- only to have "things" rupture- causing an emergency full abodominal hysterectomy on the 26th of December.
My guess is I am older than you are. However- starting with the exams may help " head this off at the pass" so to speak. Could even be something as simple as a cyst or more serious as fibroids- only the doctor knows for sure.